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1.
Chloroplasts with high rates of photosynthetic O2 evolution (up to 120 mol O2· (mg Chl)-1·h-1 compared with 130 mol O2· (mg Chl)-1·h-1 of whole cells) were isolated from Chlamydomonas reinhardtii cells grown in high and low CO2 concentrations using autolysine-digitonin treatment. At 25° C and pH=7.8, no O2 uptake could be observed in the dark by high- and low-CO2 adapted chloroplasts. Light saturation of photosynthetic net oxygen evolution was reached at 800 mol photons·m-2·s-1 for high- and low-CO2 adapted chloroplasts, a value which was almost identical to that observed for whole cells. Dissolved inorganic carbon (DIC) saturation of photosynthesis was reached between 200–300 M for low-CO2 adapted chloroplasts, whereas high-CO2 adapted chloroplasts were not saturated even at 700 M DIC. The concentrations of DIC required to reach half-saturated rates of net O2 evolution (Km(DIC)) was 31.1 and 156 M DIC for low- and high-CO2 adapted chloroplasts, respectively. These results demonstrate that the CO2 concentration provided during growth influenced the photosynthetic characteristics at the whole cell as well as at the chloroplast level.Abbreviations Chl
chlorophyll
- DIC
dissolved inorganic carbon
- Km(DIC)
coneentration of dissolved inorganic carbon required for the rate of half maximal net O2 evolution
- PFR
photon fluence rate
- SPGM
silicasol-PVP-gradient medium 相似文献
2.
The addition of 2–4% oils to the synthetic fermentation medium used for the cultivation ofStreptomyces cinnamonensis increased the production of monensin three times on the average. When the amount of the added oil was lower than 2% and higher
than 4% the production sharply decreased. The maximal production preceded the maximal consumption of individual fatty acids
of the added oils, the content of oleic acid decreasing most pronouncedly. 相似文献
3.
Heterochromatin distribution and chiasma localization in the grasshopper Bryodema tuberculata (fabr.) (Acrididae) 总被引:1,自引:0,他引:1
The problem of extreme localisation of chiasmata in the grasshopper species Bryodema tuberculata has been reinvestigated, using C-banding, Q-banding and benzimidazol techniques. These techniques reveal the precise localisation of heterochromatin in different chromosomes. Single or double heterochromatic blocks are present near the centromeric regions, except in chromosomes 5 and 11, which have larger blocks. These two chromosomes possess a distal chiasma while the other autosomes have a proximal chiasma. The results with regard to the distribution of chiasmata, in relation to the localisation of heterochromatin, as well as the existence of a short arm, are compared with the earlier observations of White, and discussed briefly. 相似文献
4.
Kl. Roemer 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1966,36(3):120-122
Zusammenfassung Unter Berücksichtigung des Fruchtformindexes h/Ø der einzelnen Frucht kann man den Volumzuwachs beliebig zusammengesetzter Gruppen von Früchten an verschiedenen Bäumen vergleichen. Bei der Berechnung der Zuwachsraten des Fruchtvolumens braucht man nur Durchmesser und Höhe der Früchte zu kennen, um das tatsächliche Volumen in guter Annäherung zu berechnen. Die Daten der Regression des Korrekturfaktors für das Volumen (K
) auf den Fruchtformindex werden für vier Sorten stark unterschiedlicher Fruchtform angegeben. Das Volumen der Frucht wird nach folgender Formel berechnet: V = 4/3 · · r
3 · K
. Vergleichende Untersuchungen über die Zuwachsrate verschiedener Sorten können bei Verwendung der sortentypischen Regressionen durchgeführt werden.
Obstbauversuchsanstalt des Alten Landes in Jork 相似文献
A method for approximate calculation of fruit volume in apples
Summary Growth rates of fruit volume can be determined more precisely by using the index h/Ø (length of fruit/diameter) than by simply calculating the volume of a sphere based on the measured diameter. Fruit volume is to be calculated by: V = 4/3 · · r 3 · K K is the factor of deviation of fruit shape from a sphere. K is given for 4 different varieties with varying shape of fruits (Echter Winterglockenapfel, Golden Delicious, Cox Orange Pippin and Ingrid Marie). The increase in volume of any group of apples within one variety or of different varieties can be compared by means of the specific regression of h/Ø to K .
Obstbauversuchsanstalt des Alten Landes in Jork 相似文献
5.
The Ca2+-activated maxi K+ channel is predominant in the basolateral membrane of the surface cells in the distal colon. It may play a role in the regulation
of the aldosterone-stimulated Na+ reabsorption from the intestinal lumen. Previous measurements of these basolateral K+ channels in planar lipid bilayers and in plasma membrane vesicles have shown a very high sensitivity to Ca2+ with a K
0.5 ranging from 20 nm to 300 nm, whereas other studies have a much lower sensitivity to Ca2+. To investigate whether this difference could be due to modulation by second messenger systems, the effect of phosphorylation
and dephosphorylation was examined. After addition of phosphatase, the K+ channels lost their high sensitivity to Ca2+, yet they could still be activated by high concentrations of Ca2+ (10 μm). Furthermore, the high sensitivity to Ca2+ could be restored after phosphorylation catalyzed by a cAMP dependent protein kinase. There was no effect of addition of
protein kinase C. In agreement with the involvement of enzymatic processes, lag periods of 30–120 sec for dephosphorylation
and of 10–280 sec for phosphorylation were observed. The phosphorylation state of the channel did not influence the single
channel conductance. The results demonstrate that the high sensitivity to Ca2+ of the maxi K+ channel from rabbit distal colon is a property of the phosphorylated form of the channel protein, and that the difference
in Ca2+ sensitivity between the dephosphorylated and phosphorylated forms of the channel protein is more than one order of magnitude.
The variety in Ca2+ sensitivities for maxi K+ channels from tissue to tissue and from different studies on the same tissue could be due to modification by second messenger
systems.
Received: 28 February 1995/Revised: 22 December 1995 相似文献
6.
Targeting of proteins to the thylakoids by bipartite presequences: CFoII is imported by a novel, third pathway. 总被引:8,自引:3,他引:5 下载免费PDF全文
The CFoII subunit of the ATP synthase is an integral component of the thylakoid membrane which is synthesized in the cytosol with a bipartite, lumen-targeting presequence similar in structural terms to those of imported lumenal proteins such as plastocyanin. This presequence is shown to possess a terminal cleavage site for the thylakoidal processing peptidase, but no intermediate site for the stromal processing peptidase. The integration of CFoII into the thylakoid membrane of Pisum sativum has been analysed using in vitro assays for the import of proteins into intact chloroplasts or isolated thylakoids. Efficient integration into thylakoids is observed in the light and dark, and the integration process does not require the presence of either stromal extracts or nucleoside triphosphates. The uncoupler nigericin inhibits integration only very slightly, indicating that the thylakoidal delta pH does not play a significant role in the integration mechanism. In each of these respects, the requirements for CFoII integration differ notably from those determined for integration of the light-harvesting chlorophyll-binding protein of photosystem II. The integration mechanism also differs significantly from the two mechanisms involved in the translocation of lumenal proteins across the thylakoid membrane, since one of these processes requires the presence of stromal protein factors and ATP, and the other mechanism is dependent on the thylakoidal delta pH. This conclusion is reinforced by the finding that saturation of the translocation system for the precursor to the lumenal 23 kDa oxygen-evolving complex protein does not affect integration of CFoII into thylakoids.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
7.
8.
Flash-induced, fast (t
1/2 1 ms), reversible reduction of the high potential cytochrome b-559 (cyt b-559HP) was observed in chloroplasts in the presence of 2 M protonophore, FCCP (carbonylcyanide p-trifluoromethoxyphenylhydrazone), CCCP (carbonylcyanide 3-chlorophenylhydrazone) or SF 6847 (2,6-di-(t-butyl)-4-(2,2-dicyanovinyl)phenol). These protonophores promote autooxidation of cyt b-559HP in the dark (Arnon and Tang 1988, Proc Natl Acad Sci USA 85: 9524). No fast photoreduction could, however, be observed if the molecules were oxidized with ferricyanide in the absence of protonophores. This suggests that the molecules must be deprotonated to be capable for fast photoreduction.Photoreduction of cyt b-559HP was largely insensitive to DBMIB (2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone), but was inhibited by DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea). With a train of flashes, no oscillation could be observed in the amplitudes of photoreduction. These data strongly suggest that cyt b-559HP is reduced by the semireduced secondary quinone acceptor (QB
–) of Photosystem 2.Abbreviations ADRY-
acceleration of the deactivation reactions of the water-splitting enzyme system Y of photosynthesis
- Ant 2p-
2-(3-chloro-4-trifluoromethyl)anilino-3,5-dinitrothiophene
- cyt-
cyto-chrome
- CCCP-
carbonylcyanide 3-chlorophenylhydrazone
- DBMIB-
2,5-dibromo-3-methyl-6-iso-propyl-p-benzoquinone
- DCMU-
3-(3,4-dichlorophenyl)-1,1-dimehtylurea
- FCCP-
carbonylcyanide p-trifluoromethoxyphenylhydrazone
- FeCy-
ferricyanide
- HP-
high potential form
- HQ-
hydroquinone
- PQ-
plastoquinone
- PS 2-
Photosystem 2
- SF 6847-
2,6-di-(t-butyl)-4-(2,2-dicyanovinyl)-phenol 相似文献
9.
10.
Andreas Klöti Victor A. Iglesias Joachim Wünn Peter K. Burkhardt Swapan K. Datta Ingo Potrykus 《Plant cell reports》1993,12(12):671-675
Summary Gene transfer into intact cells was achieved by electroporating zygotic wheat embryos without any special pretreatment. Electroporation was tissue specific in so far as scutellum cells were found to be much more susceptible to gene transfer than other cell types of the embryo. The orientation of the embryos in the electroporation chamber also influenced the number of transformed scutellum cells; during electroporation, as in electrophoresis, the negatively charged plasmid DNA molecules seemed to move towards the positive electrode. Therefore, the embryos were arranged so that the scutella faced the negative electrode. The use of plasmids carrying either two chimeric anthocyanin regulatory genes or a chimeric gusA gene allowed clear identification of transformed cells in the scutellum. On some of the embryos, more than 100 transformed scutellum cells were found after electroporation with single electric pulses of 275 V/cm discharged from a 960-F capacitor and with 100 g DNA/ml electroporation buffer. Using the anthocyanin marker system, visibly transformed cells grew to produce red sectors.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- GUS
-glucuronidase
- MES
2-N-morpholinoethane sulfonic acid 相似文献