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1.
In a greenhouse study, with and without rice plants, of five flooded Philippine rice soils whose organic C (OC) content varied
from 0.5 to 3.6%, incorporation ofSesbania rostrata, Azolla microphylla and rice straw affected the kinetics of soil solution NH
4
+
−N, K+, Fe2+, Mn2+, Zn2+, and P. Sesbania and Azolla increased NH
4
+
−N concentration above the control treatment, whereas rice straw depressed it. In all soils Azolla released less NH
4
+
−N than Sesbania. The apparent net N release depended on the soil and ranged from 44–81% for Sesbania and 27–52% for Azolla.
These effects persisted throughout the growth of IR36. Soil solution and exchangeable NH
4
+
−N increased initially but levelled off between 30 to 80 days and between 20 to 40 days after flooding (DF), respectively.
With rice, soil solution NH
4
+
−N concentration, reached a peak at 15–40 DF and declined to very low levels (<4mg L−1). In the 3 soils of low OC content nitrogen derived from green manure ranged from 34–53% and the apparent revovery of added
green manure N varied from 29–67%. Almost all N released from both Azolla and Sesbania were recovered in the rice plant in
all soils except Concepcion with only 77%. The concentration of K+, Fe2+, Mn2+ and P in the soil solution were higher with rice straw than Sesbania and Azolla in all soils except Hanggan which showed
no change in Fe2+ and Mn2+ but increased K+ and P. In general, rice straw, Sesbania and Azolla decreased Zn2+ concentration in all soils. 相似文献
2.
Pilar Ruiz-Sánchez Stefan Mundwiler Bernhard Spingler Nicole R. Buan Jorge C. Escalante-Semerena Roger Alberto 《Journal of biological inorganic chemistry》2008,13(3):335-347
Aiming at the use of vitamin B12 as a drug delivery carrier for cytotoxic agents, we have reacted vitamin B12 with trans-[PtCl(NH3)2(H2O)]+, [PtCl3(NH3)]− and [PtCl4]2−. These Pt(II) precursors coordinated directly to the Co(III)-bound cyanide, giving the conjugates [{Co}–CN–{trans-PtCl(NH3)2}]+ (5), [{Co}–CN–{trans-PtCl2(NH3)}] (6), [{Co}–CN–{cis-PtCl2(NH3)}] (7) and [{Co}–CN–{PtCl3}]− (8) in good yields. Spectroscopic analyses for all compounds and X-ray structure elucidation for 5 and 7 confirmed their authenticity and the presence of the central “Co–CN–Pt” motif. Applicability of these heterodinuclear conjugates
depends primarily on serum stability. Whereas 6 and 8 transmetallated rapidly to bovine serum albumin proteins, compounds 5 and 7 were reasonably stable. Around 20% of cyanocobalamin could be detected after 48 h, while the remaining 80% was still the
respective vitamin B12 conjugates. Release of the platinum complexes from vitamin B12 is driven by intracellular reduction of Co(III) to Co(II) to Co(I) and subsequent adenosylation by the adenosyltransferase
CobA. Despite bearing a rather large metal complex on the β-axial position, the cobamides in 5 and 7 are recognized by the corrinoid adenosyltransferase enzyme that catalyzes the formation of the organometallic C–Co bond present
in adenosylcobalamin after release of the Pt(II) complexes. Thus, vitamin B12 can potentially be used for delivering metal-containing compounds into cells.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
3.
This study examined the effects of season-long exposure of Chinese pine (Pinus tabulaeformis) to elevated carbon dioxide (CO2) and/or ozone (O3) on indole-3-acetic acid (IAA) content, activities of IAA oxidase (IAAO) and peroxidase (POD) in needles. Trees grown in
open-top chambers (OTC) were exposed to control (ambient O3, 55 nmol mol−1 + ambient CO2, 350 μmol mol−1, CK), elevated CO2 (ambient O3 + high CO2, 700 μmol mol−1, EC) and elevated O3 (high O3, 80 ± 8 nmol mol−1 + ambient CO2, EO) OTCs from 1 June to 30 September. Plants grown in elevated CO2 OTC had a growth increase of axial shoot and needle length, compared to control, by 20% and 10% respectively, while the growth
in elevated O3 OTC was 43% and 7% less respectively, than control. An increase in IAA content and POD activity and decrease in IAAO activity
were observed in trees exposed to elevated CO2 concentration compared with control. Elevated O3 decreased IAA content and had no significant effect on IAAO activity, but significantly increased POD activity. When trees
pre-exposed to elevated CO2 were transferred to elevated O3 (EC–EO) or trees pre-exposed to elevated O3 were transferred to elevated CO2 (EO–EC), IAA content was lower while IAAO activity was higher than that transferred to CK (EC–CK or EO–CK), the change in
IAA content was also related to IAAO activity. The results indicated that IAAO and POD activities in Chinese pine needles
may be affected by the changes in the atmospheric environment, resulting in the change of IAA metabolism which in turn may
cause changes in Chinese pine’s growth.
An erratum to this article can be found at 相似文献
4.
Sabine Fuhrmann Jörg Overmann Norbert Pfennig Ulrich Fischer 《Archives of microbiology》1993,160(3):193-198
The specific Bchl a and c content of the vitamin B12-dependent Chlorobium limicola strain 1230 decreased strongly under vitamin B12 limitation. In comparison to a regularly grown culture (20 g vitamin B12/l) the specific Bchl c content of a B12-limited culture was reduced to 20% and the specific Bchl a content to 42%. By ultrathin sections it could be clearly demonstrated that B12-deficient cells contained no chlorosomes. After the addition of vitamin B12 to a deficient culture, chlorosomes were formed and the Bchl a and c content increased again to the level of regularly grown cells. The brown-colored Chlorobium phaeobacteroides strain 2430 (type strain) and the extremely low-light-adapted strain MN1 were compared with respect to the influence of light on the formation of chlorosomes and the Bchl e and carotenoid content. By ultrathin sections it could be demonstrated that strain MN1 produced two-fold larger chlorosomes. Chlorosome dimensions of strain MN1 decreased with increasing light intensities. The number of chlorosomes per cell in both strains did not change with different light intensities. Strain MN1 formed twice as much Bchl e as the type strain when grown at 30 or below 1 mol · m-2 · s-1. Under comparable light conditions strain MN1 formed 14–57% more carotenoids than the type strain. Low light intensities aaused the carotenoid content to increase by 25% in strain 2430 in comparison to high light intensity. 相似文献
5.
Kun-Tai Li Dong-Hong Liu Ying-Ping Zhuang Yong-Hong Wang Ju Chu Si-Liang Zhang 《World journal of microbiology & biotechnology》2008,24(11):2525-2530
Previous research has confirmed that cobalt ion and dimethylbenzimidazole (DMBI) are the precursors of vitamin B12 biosynthesis, and porphobilinogen synthase (PBG synthase) is a zinc-requiring enzyme. In this paper, the effects of Zn2+, Co2+ and DMBI on vitamin B12 production by Pseudomonas denitrificans in shake flasks were studied. Present experimental results demonstrated that the addition of the above mentioned three components
to the fermentation medium could significantly stimulate the biosynthesis of vitamin B12. The concentrations of zinc sulphate, cobaltous chloride and DMBI in the fermentation medium were further optimized with
rotatable orthogonal central composite design and statistical analysis by Data Processing System (DPS) software. As a result,
vitamin B12 production was increased from 69.36 ± 0.66 to 78.23 ± 0.92 μg/ml. 相似文献
6.
An effect of desiccation (a decrease of relative water content from 97% to 10% within 35 h) on Photosystem II was studied
in barley leaf segments (Hordeum vulgare L. cv. Akcent) using chlorophyll a fluorescence and thermoluminescence (TL). The O-J-I-P fluorescence induction curve revealed a decrease of FP and a slight shift of the J step to a shorter time with no change in its height. The analysis of the fluorescence decline
after a saturating light flash revealed an increased portion of slow exponential components with increasing desiccation. The
TL bands obtained after excitation by continuous light were situated at about –27°C (Zv band – recombination of P680+QA
−), –14 °C (A band – S3QA
−), +12 °C (B band – S2/3QB
−) and +45 °C (C band – TyrD+QA
−). The bands related to the S-states of oxygen evolving complex (A and B) were reduced by desiccation and shifted to higher
and lower temperatures, respectively. In accordance with this, the band observed at about +27 °C (S2QB
−) after excitation by 1 flash fired at –10 °C and band at about +20 °C (S2/3QB
−) after 2 flashes decreased with increasing water deficit and shifted to lower temperatures. A new band around 5 °C appeared
in both regimes of TL excitation for a relative water content of under 42% and was attributed to the Q band (S2QA
−). It is suggested that under desiccation, an inhibition of the formation of S2- and S3-states in OEC occurred simultaneously with a lowering of electron transport on the acceptor side of PS II. The temperature
down-shift of the TL bands obtained after the flash excitation was induced at the initial phases of water stress, indicating
a decrease of the activation energy for the S2/3QB
−recombination.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
7.
We previously isolated an analog to chlorophyll-related compounds, pheophytin a, from the marine brown alga Sargassum fulvellum and demonstrated that it is a neurodifferentiation compound. In the current study, we investigated the effects of the pheophytin
a analog vitamin B12 on PC12 cell differentiation. In the presence of a low level of nerve growth factor (10 ng ml−1), vitamin B12 demonstrated neurite outgrowth-promoting activity in PC12 cells. The effect was dose-dependent in the range of 6–100 μM. In
the absence of nerve growth factor, vitamin B12 did not promote differentiation. To investigate the mechanism for this effect, we conducted differentiation assays and western
blot analysis with signal transduction inhibitors and found that vitamin B12 did not promote PC12 cell differentiation in the presence of K252a or U0126 inhibitors. These results suggest that vitamin
B12 stimulates PC12 cell differentiation through enhancement of the mitogen-activated protein kinase signal transduction pathway,
which is also induced by nerve growth factor. Thus, vitamin B12 may be a good candidate for treatment of neurodegenerative diseases such as Alzheimer’s disease. 相似文献
8.
Involvement of betacyanin in chilling-induced photoinhibition in leaves of <Emphasis Type="Italic">Suaeda salsa</Emphasis> 总被引:1,自引:0,他引:1
Seeds of Suaeda salsa were cultured in dark for 3 d and betacyanin accumulation in seedlings was promoted significantly. Then the seedlings with
accumulated betacyanin (C+B) were transferred to 14/10 h light/dark and used for chilling treatment 15 d later. Photosystem
2 (PS2) photochemistry, D1 protein content, and xanthophyll cycle during the chilling-induced photoinhibition (exposed to
5 °C at a moderate photon flux density of 500 μmol m−2 s−1 for 3 h) and the subsequent restoration were compared between the C+B seedlings and the control (C) ones. The maximal efficiency
of PS2 photochemistry (Fv/Fm), the efficiency of excitation energy capture by open PS2 centres (Fv′/Fm′), and the yield of PS2 electron transport (ΦPS2) of the C+B and C leaves both decreased during photoinhibition. However, smaller decreases in Fv/Fm, Fv′/Fm′, and ΦPS2 were observed in the C+B leaves than in C ones. At the same time, the deepoxidation state of xanthophyll cycle, indicated
by (A+Z)/(V+A+Z) ratio, increased rapidly but the D1 protein content decreased considerably during the photoinhibition. The
increase in rate of (A+Z)/(V+A+Z) was higher but the D1 protein turnover was slower in C+B than C leaves. After photoinhibition
treatment, the plants were transferred to a dim irradiation (10 μmol m−2 s−1) at 25 °C for restoration. During restoration, the chlorophyll (Chl) fluorescence parameters, D1 protein content, and xanthophyll
cycle components relaxed gradually, but the rate and level of restoration in the C+B leaves was greater than those in the
C leaves. The addition of betacyanins to the thylakoid solution in vitro resulted in similar changes of Fv/Fm, D1 protein content, and (A+Z)/(V+A+Z) ratio during the chilling process. Therefore, betacyanin accumulation in S. salsa seedlings may result in higher resistance to photoinhibition, larger slowing down of D1 protein turnover, and enhancement
of non-radiative energy dissipation associated with xanthophyll cycle, as well as in greater restoration after photoinhibition
than in the control when subjected to chilling at moderate irradiance. 相似文献
9.
The Ca2+ channel α1B subunit is a pore-forming component capable of generating N-type Ca2+ channel activity. Although the N-type Ca2+ channel plays a role in a variety of neuronal functions, α1B-deficient mice did not show apparent behavioral abnormality. In a previous study, we observed a compensatory increase of
mRNA expression of the P/Q-type Ca2+ channel α1A subunit gene in olfactory bulb of α1B-deficient mice with a CBA × C57BL/6 background; these mice showed a normal reproductive ability. In this study, we found
that the mRNA expression level of the α1A subunit was the same in olfactory bulb of wild, heterozygous, and homozygous α1B-deficient mice with a CBA/JN background, and the homozygous male mice produced no offspring. These results suggest that the
genetic background influences α1A subunit mRNA expression and reproductive ability in α1B-deficient mice. 相似文献
10.
Pilar Ruiz-Sánchez Christiane König Stefano Ferrari Roger Alberto 《Journal of biological inorganic chemistry》2011,16(1):33-44
It is attractive to use vitamin B12 as a carrier for targeted delivery of cytotoxic agents such as platinum complexes owing to the high demand for vitamin B12 by fast proliferating cells. The basic {B12–CN–PtII} conjugates are recognized by intracellular enzymes and converted to coenzyme B12 in an enzymatic adenosylation assay. The reductive adenosylation of {B12–CN–PtII} conjugates leads to the release of the PtII complexes; thus, {B12–CN–PtII} conjugates can be considered as prodrugs. It is important not only to elucidate the activity of the cisplatin–B12 conjugates, but also to understand the mode of action on a molecular level. Chemical reduction of {B12–CN–PtII} conjugates with cobaltocene yielded cob(II)alamin and induced release of the corresponding PtII species. Kurnakov tests and coordination of 2′-deoxyguanosine or GMP to the released PtII complexes allowed isolation and characterization of PtII complexes as released during enzymatic adenosylation. The biological activity of these PtII complexes was evaluated. Since the cleaved PtII complexes show cytotoxicity, the {B12–CN–PtII} conjugates can be used for specific targeting of cancer cells and therapeutic drug delivery. Preliminary in vitro cytotoxicity
studies indicated lower activity (IC50 between 8 and 88 μM) than found for pure cisplatin. Since active transport and receptor-mediated uptake limits the intracellular
{B12–CN–PtII} concentration, comparison with pure cisplatin is of limited use. We could show that the PtII complexes cleaved from B12 exerted a cytotoxicity comparable to that of cisplatin itself. Cytotoxicity studies in vitamin B12 free media showed a dependence on the addition of transcobalamin II for B12–Pt(II) conjugates. 相似文献
11.
Pharmacological and biochemical characteristics of the partially purified -aminobutyric acid (GABA)B receptor using baclofen affinity column chromatography have been examined. The Scatchard analysis of [3H]GABA binding to the purified GABAB receptor showed a linear relationship and the KD and Bmax values were 60 nM and 118 pmol/mg of protein, respectively. Although GTP and Mg2+ did not affect on the GABAB receptor binding, Ca2+ significantly increased [3H]GABA binding to the purified GABAB receptor in a dose-dependent manner and showed its maximum effect at 2 mM. The enhancement of the binding by Ca2+ was found to be due to the increase of Bmax by the Scatchard analysis. The treatments with pronase and trypsin significantly decreased the binding of [3H]GABA, but phospholipase A2 had no significant effect on the binding. In addition, treatment with glycosidases such as glycopeptidase A and -galactosidase significantly decreased the binding of [3H]GABA to the purified GABAB receptor. These results suggest that purification of the solubilized GABAB receptor by the affinity column chromatography may result in the functional uncoupling of GABAB receptor with GTP-binding protein. Furthermore, the present results suggest that cerebral GABAB receptor may be a glycoprotein and membrane phospholipids susceptible to phospholipase A2 treatment may not be involved in the exhibition of the binding activity.Special issue dedicated to Dr. Eugene Roberts. 相似文献
12.
M. V. Kustov V. V. Tsvilovskii A. V. Zholos M. F. Shuba T. B. Bolton 《Neurophysiology》2006,38(1):1-8
Using a two-wave fluorescence probe, Fura-2, we studied changes in the intracellular concentration of calcium ions ([Ca2+]i) resulting from activation of muscarinic and purine receptors in single myocytes of the guinea-pig small intestine. Applications
of the respective agonists added to the normal Krebs solution (1.0, 10.0, and 100.0 μM carbachol, CCh, as well as 10.0 and
100.0 μM ATP) induced a rise in the [Ca2+]i. Carbachol evoked an increase in the [Ca2+]i, including two components (a rapid and a plateaulike), while ATP under analogous conditions led only to a short-lasting rise
in the [Ca2+]i. Transients induced by CCh or ATP applied in different concentrations, which exceeded a certain level, did not significantly
differ from each other in their amplitudes, i.e., they were generated according to an all-or-none principle. In the nominally
Ca-and Mg-free solution, CCh and ATP induced only rapid increases in the [Ca2+]i in myocytes. The absence of the slow component in the [Ca2+]i elevation upon the action of CCh under such conditions indicates that the effect of ATP, as compared with that of CCh, is
not related to activation of the entry of Ca2+ ions into cells through voltage-operated calcium channels. After the addition of CCh, repeated application of CCh or ATP
induced no effect, while application of CCh after the addition of ATP initiated a rise in the [Ca2+]i. These data show that intracellular calcium stores are depleted completely upon the action of CCh, while they are depleted
only partially after the action of ATP. An inhibitor of phospholipase C (PLC), U-73122 (5.0 μM), completely blocked rises
in the [Ca2+]i induced by both CCh and ATP; therefore, the release of Ca2+ ions from the intracellular calcium stores after application of these agonists is mediated by PLC. We hypothesize that the
difference in the release of Ca2+ ions from the intracellular stores observed in our experiments upon activation of choline and purine receptors (partial and
complete depletion of the stores upon the action of ATP and CCh, respectively) is responsible for the opposite functional
effects of the above-mentioned neurotransmitters on smooth muscles.
Neirofiziologiya/Neurophysiology, Vol. 38, No. 1, pp. 3–10, January–February, 2006. 相似文献
13.
The vitamin B12 requirement of Rhodocyclus purpureus 6770, Rhodospirillum tenue 1/67, and Rhodopseudomonas palustris G 53/2 was determined. A wide variety of biogenetic precursors of the vitamin including cobinamide, cobyric acid, cobinic acid and several partially amidated cobyrinic acids showed growth-promoting activity in all three strains. In R. purpureus vitamin B12 could even be substituted by cobyrinic acid which is the first cobalt-containing precursor of vitamin B12 so far established. Neither methionine, deoxynucleosides, dimethylbenzimidazole nor increased amounts of cobalt could replace vitamin B12 as growth factor.Cupribalamin, which is a strong antimetabolite of vitamin B12 in Escherichia coli 113-3 and Lactobacillus leichmannii ATCC 7830, exhibited only a weak antagonistic effect on growth of R. purpureus and R. tenue. Growth of R. palustris was not inhibited by cupribalamin. The cells of all three strains were shown to contain metal-free corrinoids in addition to cobalt-containing corrinoids. The principal products were identified as 5-deoxyadenosylcobalamin and hydrogenobalamin, the metal free analogue of vitamin B12. The latter does not originate from the vitamin by removal of cobalt but is de novo biosynthesized as could be demonstrated in the case of R. purpureus by a labelling experiment with [13C] methyl-l-methionine. 相似文献
14.
Contessi S Comelli M Cmet S Lippe G Mavelli I 《Journal of bioenergetics and biomembranes》2007,39(4):291-300
F0F1ATPsynthase is now known to be expressed as a plasma membrane receptor for several extracellular ligands. On hepatocytes,
ecto–F0F1ATPsynthase binds apoA–I and triggers HDL endocytosis concomitant with ATP hydrolysis. Considering that inhibitor protein
IF1 was shown to regulate the hydrolytic activity of ecto–F0F1ATPsynthase and to interact with calmodulin (CaM) in vitro, we investigated the subcellular distributions of IF1, calmodulin (CaM), OSCP and β subunits of F0F1ATPsynthase in HepG2 cells. Using immunofluorescence and Western blotting, we found that around 50% of total cellular IF1 is localized outside mitochondria, a relevant amount of which is associated to the plasma membrane where we also found Ca2+–CaM, OSCP and β. Confocal microscopy showed that IF1 colocalized with Ca2+–CaM on plasma membrane but not in mitochondria, suggesting that Ca2+–CaM may modulate the cell surface availability of IF1 and thus its ability to inhibit ATP hydrolysis by ecto–F0F1ATPsynthase. These observations support a hypothesis that the IF1–Ca2+–CaM complex, forming on plasma membrane, functions in the cellular regulation of HDL endocytosis by hepatocytes. 相似文献
15.
Prion diseases are a group of neurodegenerative illnesses caused by conformational conversion of benign, α-helix rich cellular
prion protein (PrPC) into the highly stable, β-sheet rich scrapie prion protein (PrPSc) isoform. To date, the role of RNA on the conformational conversion of ovine prion protein in vitro remains unknown. To examine
the effect of the interaction between RNA and PrPC, conformations of recombinant ovine prion protein PrP23–256 (OvPrP23–256) binding various concentrations of RNA were analyzed by circular dichroism (CD) spectrum. The results indicated that the
conformational conversion of OvPrP23–256 was triggered by RNA with a decrease in α-helix content and increase in β-sheet. Moreover, the conformation of OvPrP23–256 interacting with both RNA and CuCl2 was also examined by CD spectrum, which showed that α-helix content decreased while β-sheet increased dramatically. Proteinase
K digestion assay disclosed that the recombinant ovine PrPC acquired PK resistance after RNA and/or Cu2+ treatment. It confirmed that the RNA/Cu2+ treatment in vitro altered the biochemical properties of ovine PrPC. The implication of this finding, with respect to PrPSc, is that a dysfunctional state of a normal physiological process possibly facilitates diseases. The information gained from
this study may provide useful approaches to study the pathogenesis of prion diseases. 相似文献
16.
Sagaya Selva Kumar 《Analytical biochemistry》2009,388(2):312-246
In the current article, chemiluminescence (CL) from the vitamin B12 and luminol reaction was studied under alkaline conditions to develop a sensitive analytical method for vitamin B12 using the carbonate enhancement effect. The method was successfully applied to the determination of vitamin B12 in vitamin B12 tablets, multivitamin capsules, and vitamin B12 injections. Experimental parameters were optimized, including luminol concentration, urea-hydrogen peroxide (urea-H2O2) concentration, effect of pH, and sequence of addition of reactants for obtaining maximum CL, which was not explored previously. The limit of detection was 5 pg/ml, and the linear range was 10 pg/ml to 1 μg/ml with a regression coefficient of R2 = 0.9998. The importance of these experimental parameters and the carbonate enhancement effect is discussed based on the knowledge of the mechanism of oxidation of luminol and decomposition of urea-H2O2 in the presence of vitamin B12. Extraction of vitamin B12 was carried out, and the observed recovery was 97-99.2% with a relative standard deviation in the range of 0.30-1.09%. The results obtained were compared with those of the flame atomic absorption spectrometry method. 相似文献
17.
R. P. Tiwari T. C. Bhalla S. S. Saini G. Singh D. V. Vadehra 《Journal of biosciences》1986,10(1):145-151
The inhibitory effects of aflatoxin B1 were found to be related to the gram character in procaryotes, used in this study. Ethylene diamine tetra chloroacetic acid
(0.05% w/v) or Tween-80 (0.05 % v/v) addition accentuated the aflatoxin B1 growth inhibition inSalmonella typhi andEscherichia coli at different pH values. The inhibition of lipase production was only 5–20 % inPseudomonas fluorescence ca. 25–48% inStaphylococcus aureus andBacillus cereus at different aflatoxin B1 concentrations (4–16μg/ml).However, inhibition of α-amylase induction was complete in1Bacillus megaterium whereas the inhibition was partial inPseudomonas fluorescence (27–40%) at 32μg aflatoxin B1 concentration. An increase in leakage of cell contents and decreased inulin uptake were observed in toxin incubated sheep
red blood cell suspension (1 %) with increased aflatoxin B1 concentration 相似文献
18.
D. Glenn Kennedy W. John Blanchflower Paul B. Young W. Brian Davidson 《Biological trace element research》1992,35(2):153-166
The first development of an α-face-specific radioimmunoassay for vitamin B12 is described. Sheep, fed a cobalt-deficient diet, and immunized with a conjugate between Co-β carboxypropyl cobalamin and
keyhole limpet hemocyanin, were used to produce antisera. The antisera crossreacted with Co-β derivatives of vitamin B12, but did not crossreact with the α-face vitamin B12 analog cobinamide. The antisera were used to develop a sensitive and reproducible radioimmunoassay that was free from contamination
with the nonspecific vitamin B12 binding protein, R-protein. Both the radioimmunoassay and measurements of plasma concentrations of methylmalonic acid were
applied to the diagnosis of cobalt/vitamin B12 deficiency in sheep. The assay correlated well with a commercially available radioassay and did not falsely detect normal
vitamin B12 concentration in plasma samples containing elevated concentrations of methylmalonic acid. 相似文献
19.
Theophilus M. Mutui Vallantino E. Emongor Margaret J. Hutchinson 《Plant Growth Regulation》2006,48(3):207-214
Leaf yellowing is a major problem in Alstroemeria and absence of leaf senescence symptoms is an important quality attribute. Two Alstroemeria cultivars ‘Yellow King’ and ‘Marina’ were sourced from a commercial farm and harvested when sepals began to reflex. Stems
were re-cut under water and kept in vase solutions of gibberellin A4+7 (0, 2.5, 5.0, 7.5, 10.0, 12.5 or 15.0 mg l−1 [Provider]). Treatments and cultivars were combined in a factorial fashion and arranged in a completely randomised design. Application
of GA4+7 in the holding solution at 2.5–10.0 mg l−1 significantly delayed the onset of leaf senescence by around 7 days and significantly increased days to 50% petal fall by
ca. 2 days. Additionally, these GA4+7 concentrations resulted in higher retention of leaf nitrogen, leaf chlorophyll and also increased leaf water content, while
reducing leaf dry weight, all relative to untreated controls. Cultivar ‘Yellow King’ had significantly longer vase life and
a better retention of leaf quality than ‘Marina’. Our results suggest that a concentration of 10 mg l−1 GA4+7 can be used to prolong vase life, delay leaf senescence and enhance post-harvest quality of Alstroemeria cut flowers during their transport to market. 相似文献
20.
The human formyl peptide receptor like 1 (FPRL-1) is a variant of the Gi-coupled formyl-peptide receptor. Functional FPRL-1 is endogenously expressed in the U87 astrocytoma cell line and there is
accumulating evidence to suggest that FPRL-1 may be involved in neuroinflammation associated with the pathogenesis of Alzheimer’s
disease. In this study, we examined the ability of FPRL-1 to mobilize intracellular Ca2+ in U87 astrocytoma cells, as well as in Chinese hamster ovary (CHO) cells stably expressing FPRL-1. We showed that Trp–Lys–Tyr–Met–Val–Met–NH2 (WKYMVM), a specific agonist for FPRL-1, stimulated Ca2+ influx in both U87 and FPRL-1/CHO cells. These effects can be inhibited by the FPRL-1 selective antagonist, WRW4. Involvement of Gi proteins was demonstrated with the use of pertussis toxin, while inhibitors of store-operated channels (SOC) including 1-[2-(4-methoxyphenyl)]-2-[3-(4-methpxyphenyl)propoxy]ethyl-1H-imidazole hydrochloride (SKF96365) and 2-aminoethoxydiphenyl borate (2-APB) were found to abolish the WKYMVM-induced Ca2+ increase. However, intracellular Ca2+ mobilization in both cell lines were unaffected by the phospholipase Cβ inhibitor U73122 or selective ryanodine receptor
inhibitors. Our data demonstrated that activation of Gi-coupled FPRL-1 can lead to Ca2+ influx possibly via SOCs in U87 and FPRL-1/CHO cells. 相似文献