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1.
A system of intracellular peptidoglycan hydrolases of Xanthomonas campestris XL-1 comprises about 10 enzymes of different localization and substrate specificity. Seven enzymes (A 1-A 7) are localized in cytosol, one enzyme (A 8) in periplasm, and two enzymes (A 9, A 10) were found in the fraction of cell walls and membranes. While the culture is entering the logarithmic growth stage from the stationary stage, a change occurs in the activity of the cytosolic enzymes: A 1 significantly increases, and A 5 and A 6 decrease. The spectrum of cytosolic enzymes also depends on the growth medium composition. The enzyme A 7 present in cells secreting extracellular enzymes (medium 5/5) was not found in non-secreting cells (LB medium). Unlike extracellular enzymes, intracellular peptidoglycan hydrolases are primarily acidic proteins. The data indicate that the system of intracellular peptidoglycan hydrolases of X. campestris is under complex and strict regulation. 相似文献
2.
Summary The binding of Rhizobium meliloti strains A 2 (effective) and V 6 (ineffective), Agrobacterium tumefaciens strain B 6S 3 and R. trifolii strain TL 5 to lucerne seedling roots was studied by using 14C or 3H-labelled bacteria. When added singly or in combination with the heterologous bacteria, the number of A 2 cells attached to the roots was significantly less than the number of B 6S 3 or TL 5 cells. However, the presence of the heterologous bacteria did not decrease the proportion of A 2 cells added in the inoculum that bind to the roots, suggesting that R. meliloti is attached to specific sites. In fact, the same number of A 2 or V 6 cells bind to the roots and in mixed inoculation the 2 strains share equally the binding sites. When added to the seedlings growth medium NO
3
–
at 5 or 16 mM significantly decreased the number of A 2 cells adhering to lucerne seedling roots. The results suggest that the lectin-recognition hypothesis is probably involved in the attachment of R. meliloti to lucerne seedling roots.Contribution No. 252 Station de recherches, Agriculture Canada 相似文献
3.
In Britton‐Robinson (BR) buffer medium (pH 3.3), carbazochrome sodium sulfonate (CSS) can react with some aromatic amino acids such as tryptophan (Trp), tyrosine (Tyr) and phenylalanine (Phe) to form a 1:1 complex by electrostatic attraction, aromatic stacking interaction and Van der Waals' force, resulting in fluorescence quenching of these amino acids. Maximum quenching wavelengths were located at 352 nm (CSS‐Trp system), 303 nm (CSS‐Tyr system) and 284 nm (CSS‐Phe system), respectively. The fluorescence quenching value (Δ F) was proportional to the concentration of CSS in a certain range. The fluorescence quenching method for the determination of CSS showed high sensitivity, with detection limits of 31.3 ng/mL (CSS‐Trp system), 44.6 ng/mL (CSS‐Tyr system) and 315.0 ng/mL (CSS‐Phe system), respectively. The optimum conditions of the reaction conditions and the effect of coexisting substances were investigated and results showed that the method had good selectivity. The method was successfully applied for the rapid determination of CSS in blood and urine samples. Based on the bimolecular quenching constant Kq, the effect of temperature and Stern‐Volmer plots, this study showed that quenching of fluorescence of amino acids by CSS was a static quenching process. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
4.
Using chromosome substitution strains (CSS), we previously identified a large quantitative trait locus (QTL) for conditioned fear (CF) on mouse chromosome 10. Here, we used an F 2 cross between CSS‐10 and C57BL/6J (B6) to localize that QTL to distal chromosome 10. That QTL accounted for all the difference between CSS‐10 and B6. We then produced congenic strains to fine‐map that interval. We identified two congenic strains that captured some or all the QTL. The larger congenic strain (Line 1: 122.387121–129.068 Mb; build 37) appeared to account for all the difference between CSS‐10 and B6. The smaller congenic strain (Line 2: 127.277–129.068 Mb) was intermediate between CSS‐10 and B6. We used haplotype mapping followed by quantitative polymerase chain reaction to identify one gene that was differentially expressed in both lines relative to B6 ( Rnf41) and one that was differentially expressed between only Line 1 and B6 ( Shmt2). These cis‐eQTLs may cause the behavioral QTLs; however, further studies are required to validate these candidate genes. More generally, our observation that a large QTL mapped using CSS and F 2 crosses can be dissected into multiple smaller QTLs shows a weaknesses of two‐stage approaches that seek to use coarse mapping to identify large regions followed by fine‐mapping. Indeed, additional dissection of these congenic strains might result in further subdivision of these QTL regions. Despite these limitations, we have successfully fine‐mapped two QTLs to small regions and identified putative candidate genes, showing that the congenic approach can be effective for fine‐mapping QTLs . 相似文献
5.
Immature embryos of inbred maize ( Zea mays) lines (H8183, H8184, and H8185) were used for Agrobacterium infection. We used the β-glucuronidase gene ( GUS) as the target gene and the glufosinate resistance gene ( bar) as the selection marker. We conducted research on several aspects, such as different genotypes, coculture conditions, screening agent concentrations, and concentrations of indole-3-butytric acid (IBA), 6-benzylaminopurine (6-BA), and ascorbic acid (Vc) in the differentiation medium. We optimized the genetic transformation system, and the obtained results indicated that among the three lines studied, the induction rate of H8185 was the highest at 93.2%, followed by H8184, with H8183 having the lowest induction rate (80.1%). The best coculture method was that using the N6 coculture medium layered with a sterile filter paper. Using orthogonal analysis, we found that the optimal combination of the three factors in the differentiation medium was A 3 (1 mg mL −1 IBA), B 3C 1 (1.6 mg mL −1 6-BA), and D 3 (1.5 mg mL −1 Vc). Through GUS staining analysis, Bar test-strip analysis, and polymerase chain reaction, five transgenic plants were finally obtained. This study established the optimal conditions for genetic transformation in maize. 相似文献
6.
This report describes the successful plant regeneration via somatic embryogenesis from immature zygotic embryos of Cryptomeria japonica D. Don. For the induction of embryogenic tissue, we determined that the optimal medium contained N 6-benzyladenine and 2,4-dichlorophenoxyacetic acid. Immature zygotic embryos that were collected at the end of June yielded embryogenic tissue at the highest frequency. Embryogenic tissues that had proliferated in liquid medium included small and loosely packed cells and elongating or elongated cells. We used ten cell lines to determine the optimal medium for the development of somatic embryos. Induced somatic embryos germinated with synchronous sprouting of cotyledons, hypocotyls and roots. Gibberellin A 3 in the germination medium had a positive effect on both the elongation of hypocotyls and the survival of seedlings. The frequencies of induction and germination of somatic embryos differed among the cell lines examined. Most of the seedlings grew normally. This system of somatic embryogenesis required 4–5 months for the regeneration of C. japonica plantlets from immature zygotic embryos.Abbreviations ABA Abscisic acid - BA N6-Benzyladenine - 2,4-D 2,4-Dichlorophenoxyacetic acid - GA3 Gibberellin A 3Communicated by F. Sato 相似文献
7.
The effect of corn stunt spiroplasma (CSS) on survival and fecundity of three Dalbulus leafhopper species was determined. CSS significantly reduced the survival, as measured by the time to 50% ( t50) and 25% ( t25) survival, and by the scale parameter ( b) of the Weibull model, for D. elimatus and D. gelbus. Fecundity of these two species, as measured by the net and gross reproductive rates, was also reduced by CSS. CSS did not significantly affect the corn leafhopper, D. maidis. In a separate experiment, maize bushy stunt mycoplasma (MBSM) reduced the survival and fecundity of D. maidis at temperatures from 20 to 29 °C. The effect of MBSM on D. maidis survival was less severe than CSS on D. elimatus and D. gelbus; t25, but not t50, was reduced by MBSM. Survival times and the cohort generation time generally declined with increasing temperature. Fecundity, however, generally increased with increasing temperature. 相似文献
8.
The production of gibberellin A 7 by Gibberella fujikuroi was studied by using newly devised assay method. Gibberellin A 7 increased at preferable temperature range between 32°C and 34°C at the controlled pH(6.0~7.5). The improved isolation process by using column chromatography composed of granular charcoal was found to be extremely convenient, because of its quick elution with satisfactory separation from gibberellic acid which is always accompanied by gibberellin A 7 in culture medium. 相似文献
9.
We have previously demonstrated that in A 6 renal epithelial cells, a commonly used model of the mammalian distal section of the nephron, adenosine A 1 and A 2A receptor activation modulates sodium and chloride transport and intracellular pH (Casavola et al., 1997). Here we show that
apical addition of the A 3 receptor-selective agonist, 2-chloro-N 6-(3-iodobenzyl)-adenosine-5′-methyluronamide (Cl-IB-MECA) stimulated a chloride secretion that was mediated by calcium- and
cAMP-regulated channels. Moreover, in single cell measurements using the fluorescent dye Fura 2-AM, Cl-IB-MECA caused an increase
in Ca 2+ influx. The agonist-induced rise in [Ca 2+]
i
was significantly inhibited by the selective adenosine A 3 receptor antagonists, 2,3-diethyl-4,5-dipropyl-6-phenylpyridine-3-thiocarboxylate-5-carboxylate (MRS 1523) and 3-ethyl 5-benzyl
2-methyl-6-phenyl-4-phenylethynyl-1,4-(±)-dihydropyridine-3,5-dicarboxylate (MRS 1191) but not by antagonists of either A 1 or A 2 receptors supporting the hypothesis that Cl-IB-MECA increases [Ca 2+]
i
by interacting exclusively with A 3 receptors. Cl-IB-MECA-elicited Ca 2+ entry was not significantly inhibited by pertussis toxin pretreatment while being stimulated by cholera toxin preincubation
or by raising cellular cAMP levels with forskolin or rolipram. Preincubation with the protein kinase A inhibitor, H89, blunted
the Cl-IB-MECA-elicited [Ca 2+]
i
response. Moreover, Cl-IB-MECA elicited an increase in cAMP production that was inhibited only by an A 3 receptor antagonist. Altogether, these data suggest that in A 6 cells a G
s
/protein kinase A pathway is involved in the A 3 receptor-dependent increase in calcium entry.
Received: 9 March 2000/Revised: 14 August 2000 相似文献
10.
Using different explants of in vitro seed grown Scutellaria baicalensis Georgi plantlets, hairy roots were induced following inoculation of Agrobacterium rhizogenes strains A 4GUS, R1000 LBA 9402 and ATCC11325. The A 4GUS proved to be more competent than other strains and the highest transformation rates were observed in cotyledonary leaf
explant (42.6 %). The transformed roots appeared after 15–20 d of incubation on hormone free Murashige and Skoog medium. Growth
of hairy roots was assessed on the basis of total root elongation, lateral root density and biomass accumulation. Maximum
growth rate was recorded in root:medium ratio 1:100 (m/v). Hairy root lines were further established in Gamborg B 5 medium and the biomass increase was maximum from 15 to 30 d. PCR, Southern hybridization and RT-PCR confirmed integration
and expression of left and right termini-linked Ri T-DNA fragment of the Ri plasmid from A 4GUS into the genome of Scutellaria baicalensis hairy roots. GUS assay was also performed for further integration and expression. All the clones showed higher growth rate
them non-transformed root and accumulated considerable amounts of the root-specific flavonoids. Baicalin content was 14.1–30.0
% of dry root mass which was significantly higher then that of control field grown roots (18 %). The wogonin content varies
from 0.08 to 0.18 % among the hairy root clones which was also higher than in non-transformed roots (0.07 %). 相似文献
12.
Gibberellins A 4, A 9, and A 24 were isolated and identified from the new gibberellin-producing fungus, Phaeosphaeria sp. L487 (Loculoascomycetes), cultivated in a chemically defined medium; their yields from the culture filtrate were ca. 1. 7, 0. 3, and 0.4 μg/ml, respectively. Gibberellins A 4 and A 9 significantly stimulated the hypocotyl growth of Chinese cabbage seedlings at a very low concentration of less than 0.01 μg/ml. 相似文献
13.
Somatic embryogenesis was induced in callus tissues derived from young flower buds of Panax notoginseng via callus within 18 weeks of culture. The mature somatic embryos were germinated on half-strength Murashige and Skoog's (MS) medium supplemented with gibberellic acid A 3(GA) and 6-benzyladenine (BA). The most suitable medium for optimal root formation proved to be MS medium supplemented with 1-naphthaleneacetic acid (NAA). Total DNA was extracted from the leaves of the regenerated plantlets of P. notoginseng. Analysis of random-amplified polymorphic DNA (RAPD) using 21 arbitrary oligonucleotide 10-mers, showed the genetic homogeneity of P. notoginseng. The amplification products were monomorphic for all of the plantlets of P. notoginseng regenerated by embryogenesis, suggesting that somatic embryogenesis can be used for clonal micropropagation of this plant. 相似文献
14.
Previously, we have reported that the coronary reactive hyperemic response was reduced in adenosine A2A receptor-null (A2AAR?/?) mice, and it was reversed by the soluble epoxide hydrolase (sEH) inhibitor. However, it is unknown in aortic vascular response, therefore, we hypothesized that A2AAR-gene deletion in mice (A2AAR?/?) affects adenosine-induced vascular response by increase in sEH and adenosine A1 receptor (A1AR) activities. A2AAR?/? mice showed an increase in sEH, AI AR and CYP450-4A protein expression but decrease in CYP450-2C compared to C57Bl/6 mice. NECA (adenosine-analog) and CCPA (adenosine A1 receptor-agonist)-induced dose-dependent vascular response was tested with t-AUCB (sEH-inhibitor) and angiotensin-II (Ang-II) in A2AAR?/? vs. C57Bl/6 mice. In A2AAR?/?, NECA and CCPA-induced increase in dose-dependent vasoconstriction compared to C57Bl/6 mice. However, NECA and CCPA-induced dose-dependent vascular contraction in A2AAR?/? was reduced by t-AUCB with NECA. Similarly, dose-dependent vascular contraction in A2AAR?/? was reduced by t-AUCB with CCPA. In addition, Ang-II enhanced NECA and CCPA-induced dose-dependent vascular contraction in A2AAR?/? with NECA. Similarly, the dose-dependent vascular contraction in A2AAR?/? was also enhanced by Ang-II with CCPA. Further, t-AUCB reduced Ang-II-enhanced NECA and CCPA-induced dose-dependent vascular contraction in A2AAR?/? mice. Our data suggest that the dose-dependent vascular contraction in A2AAR?/? mice depends on increase in sEH, A1AR and CYP4A protein expression. 相似文献
15.
Abstract: The binding of [ 3H]rauwolscine to α 2A- (also referred to as α 2D-) and α 2C-adrenoceptors in homogenates of rat cerebral cortex was measured by exploiting the selectivity of oxymetazoline for α 2A-adrenoceptors. Inhibition of [ 3H]rauwolscine binding by oxymetazoline was modeled best assuming binding to two sites ( p < 0.001). Competition curves for oxymetazoline were shifted rightward by the addition of GTP (250 µ M) but were still fit best by a two-site model ( p < 0.001). A concentration of oxymetazoline was calculated that would optimally antagonize [ 3H]rauwolscine binding (with GTP present) to oxymetazoline-sensitive α 2A-adrenoceptors, minimally inhibiting binding to α 2C-adrenoceptors. Subsequently, [ 3H]rauwolscine binding to α 2A- and α 2C-adrenoceptors in cortex was examined 3 weeks after destruction of noradrenergic terminals. Binding to α 2C-adrenoceptors was increased significantly after treatment with 6-hydroxydopamine (6-OHDA) compared with vehicle-treated controls, whereas binding to α 2A-adrenoceptors was unchanged. Pretreatment of rats with desipramine before 6-hydroxydopamine, to protect noradrenergic neurons, resulted in no changes in binding to either α 2A- or α 2C-adrenoceptors. Thus, α 2C-adrenoceptors are regulated by changes in synaptic availability of norepinephrine. α 2A-Adrenoceptors are either not regulated by synaptic norepinephrine or are located both post- and presynaptically so that up-regulation of postsynaptic α 2A-adrenoceptors is offset by a loss of presynaptic α 2A-adrenoceptors. 相似文献
16.
A simple and easy transformation strategy was accomplished on field growing plants of Phyllanthus amarus, an anti-hepatitis B drug plant. Infection of Agrobacterium rhizogenes strains A 4M70GUS and ATCC 15834 on decapitated shoots of field growing P. amarus induced hairy roots and crown gall, respectively. Infection with A 4M70GUS yielded a mean of 23.2 roots from 40% plants in 40-day period. The crown gall induced on 30% plants after infection
with ATCC 15834 grew to 5–10 mm in diameter. The roots and crown galls established in vitro on Murashige and Skoog (MS) basal
medium grew well. The hairy roots yielded fivefold (6.91 g) biomass in half-strength MS liquid medium to that of the adventitious
roots derived from internode explants in MS medium with 8.0 μM α-naphthaleneacetic acid (1.39 g). Histochemical assay and
PCR analysis using the primers of uidA coding region confirmed the hairy roots induced by A 4M70GUS. The crown galls induced by ATCC 15834 were confirmed by PCR analysis using rolB gene primers. The protocol enables an easy and early accomplishment of hairy roots. 相似文献
17.
We have shown that triterpene glycosides of the Far Eastern edible holothurian Cucumaria japonica (monosulfated subfractions A
2 and A
4, disulfated subfraction A
6, trisulfated subfraction A
7, and the total fraction of monosulfated glycosides including subfractions A
0, A
1, A
2, and A
4) inhibited growth of the main root of Cucumis sativus seedlings. Cucumariosides were arranged as follows according to their inhibitory activity: subfraction A
2 (ED 50 = 53 .1 ± 3 .6 g/ml) > total fraction of monosulfated glycosides (ED 50 = 127 .4 ± 5 .8 g/ml) > subfraction A
4 (ED 50 = 346.5 ± 15.2 g/ml) > subfraction A
6 (ED 50 = 375.7 ± 17.2 g/ml) > subfraction A
7 (ED 50 = 539 .4 ± 11 .5 g/ml). The average length of the main root decreased with the increase of glycoside concentrations as a result of a growing amount of seedlings with low germination capacity and the absence of seedlings with high germination capacity. 相似文献
18.
New 7-amino-2-phenylpyrazolo[4,3- d]pyrimidine derivatives, substituted at the 5-position with aryl(alkyl)amino- and 4-substituted-piperazin-1-yl- moieties, were synthesized with the aim of targeting human (h) adenosine A 1 and/or A 2A receptor subtypes. On the whole, the novel derivatives 1– 24 shared scarce or no affinities for the off-target hA 2B and hA 3 ARs. The 5-(4-hydroxyphenethylamino)- derivative 12 showed both good affinity ( Ki =?150?nM) and the best selectivity for the hA 2A AR while the 5-benzylamino-substituted 5 displayed the best combined hA 2A ( Ki =?123?nM) and A 1 AR affinity ( Ki =?25?nM). The 5-phenethylamino moiety (compound 6) achieved nanomolar affinity ( Ki =?11?nM) and good selectivity for the hA 1 AR. The 5-(N 4-substituted-piperazin-1-yl) derivatives 15– 24 bind the hA 1 AR subtype with affinities falling in the high nanomolar range. A structure-based molecular modeling study was conducted to rationalize the experimental binding data from a molecular point of view using both molecular docking studies and Interaction Energy Fingerprints (IEFs) analysis. 相似文献
19.
Development of the relationship between leaf area ( A
l
) and sapwood area ( A
s
) was investigated in two important hardwoods, Eucalyptus globulus (Labill) and E. nitens (Deane and Maiden) Maiden, growing in an experimental plantation established in a low rainfall zone (approx. 515 mm year –1) of Tasmania. The experiment compared irrigated controls and a rainfed treatment which was subjected to cyclical summer droughts
from age 1 to 6 years old. Leaf area and sapwood area were determined by destructive sampling at ages 2, 3 and 6 years old.
There was no effect of stand age on A
l
:A
s
when sapwood area was measured at crown break. At age 3 years old A
l
:A
s
was significantly greater in the rainfed than the irrigated trees. It was concluded that this difference was due to earlier
canopy closure in the irrigated trees. When the plantation was 6 years old A
l
:A
s
was significantly greater in the irrigated than the rainfed treatment. An analysis based on an equation which links A
l
:A
s
with transpiration and volumetric flow rate (Whitehead et al. 1984) was used to infer a positive correlation between stem
hydraulic conductivity ( k
h
) and water availability. Independent of water availability E. globulus maintained a higher A
l
:A
s
than E. nitens at all ages.
Received: 20 March 1997 / Accepted: 30 December 1997 相似文献
20.
Adenosine is a biologically active molecule that is formed at sites of metabolic stress associated with trauma and inflammation,
and its systemic level reaches high concentrations in sepsis. We have recently shown that inactivation of A 2A adenosine receptors decreases bacterial burden as well as IL-10, IL-6, and MIP-2 production in mice that were made septic
by cecal ligation and puncture (CLP). Macrophages are important in both elimination of pathogens and cytokine production in
sepsis. Therefore, in the present study, we questioned whether macrophages are responsible for the decreased bacterial load
and cytokine production in A 2A receptor-inactivated septic mice. We showed that A 2A KO and WT peritoneal macrophages obtained from septic animals were equally effective in phagocytosing opsonized E. coli. IL-10 production induced by opsonized E. coli was decreased in macrophages obtained from septic A 2A KO mice as compared to WT counterparts. In contrast, the release of IL-6 and MIP-2 induced by opsonized E. coli was higher in septic A 2A KO macrophages than WT macrophages. These results suggest that peritoneal macrophages are not responsible for the decreased
bacterial load and diminished MIP-2 and IL-6 production that are observed in septic A 2A KO mice. In contrast, peritoneal macrophages may contribute to the suppressive effect of A 2A receptor inactivation on IL-10 production during sepsis. 相似文献
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