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991.
Battistuzzi G Bellei M Zederbauer M Furtmüller PG Sola M Obinger C 《Biochemistry》2006,45(42):12750-12755
Myeloperoxidase (MPO) (donor, hydrogen peroxide oxidoreductase, EC 1.11.1.7) is the most abundant neutrophil enzyme and catalyzes predominantly the two-electron oxidation of ubiquitous chloride (Cl-), to generate the potent bleaching oxidant hypochlorous acid (HOCl), thus contributing to bacterial killing and inflammatory reactions of neutrophils. Here, the thermodynamics of the one-electron reduction of the ferric heme in its ferric high-spin and cyanide-bound low-spin forms were determined through spectroelectrochemical experiments. The E(o)' values for free and cyanide-bound MPO (5 and -37 mV, respectively, at 25 degrees C and pH 7.0) are significantly higher than those of other heme peroxidases. Variable-temperature experiments revealed that the enthalpic stabilization of ferric high-spin MPO is much weaker than in other heme peroxidases and is exactly compensated by the entropic change upon reduction. In contrast to those of other heme peroxidases, the stabilization of the ferric cyanide-bound MPO is also very weak and fully entropic. This peculiar behavior is discussed with respect to the MPO-typical covalent heme to protein linkages as well as to the published structures of ferric MPO and its cyanide complex and the recently published structure of lactoperoxidase as well as the physiological role of MPO in bacterial killing. 相似文献
992.
High genetic diversity detected in the endemic Primula apennina Widmer (Primulaceae) using ISSR fingerprinting 总被引:3,自引:0,他引:3
Silvia Crema Giovanni Cristofolini Martina Rossi Lucia Conte 《Plant Systematics and Evolution》2009,280(1-2):29-36
Primula apennina Widmer is endemic to the North Apennines (Italy). ISSR were used to detect the genetic diversity within and among six populations representative of the species distribution range. High levels of genetic diversity were revealed both at population percentage of polymorphic band (PPB = 75.92%, H S = 0.204, H pop = 0.319) and at species level (PPB = 96.95%, H T = 0.242, H sp = 0.381). Nei gene diversity statistics (15.7%), Shannon diversity index (16.3%) and AMOVA (14%) detected a moderate level of interpopulation diversity. Principal coordinate and Bayesian analyses clustered the populations in three major groups along a geographic gradient. The correlation between genetic and geographic distances was positive (Mantel test, r = 0.232). All together, these analyses revealed a weak but significant spatial genetic structure in P. apennina, with gene flow acting as a homogenizing force that prevents a stronger differentiation of populations. Conservation measures are suggested based on the observed pattern of genetic variability. 相似文献
993.
Radovan J Vaclav P Petr W Jan C Michal A Richard P Martina P 《Molecular and cellular biochemistry》2006,293(1-2):71-78
Objectives: To analyze the predictive value of cardiac collagen metabolism “in vivo" in patients with myocardial infarction (MI) treated with percutaneous coronary intervention (PCI). Design: Forty-five patients (age 66 ± 8.27) underwent biochemical analysis for cardiac collagen metabolism (groups A, B and C); 30 patients with their first MI were treated with successful PCI (group A; n = 30), group B (n = 5) were MI patients with unsuccessful PCI. Group C were patients without MI (n = 10), they underwent elective diagnostic coronary angiography only. The collagen metabolism was analyzed in acute and subacute MI phases by using serum blood markers: the carboxy-terminal propeptide of type I procollagen (PICP), amino-terminal propeptide of type III procollagen (PIIINP) and carboxy-terminal telopeptide of type I collagen (ICTP). Furthermore, the ejection fraction (EF) and left ventricular end-diastolic volume maximal changes in the course of 6 months were measured by echocardiography. Results: A significant increase of both PICP and PIIINP on day 4 following MI was detected. Furthermore, PICP and PIIINP level assessed on the 30th day was significantly higher in the PCI unsuccessful group versus successful group. PICP level on day 4 above 110 ug/l and PIIINP level above 4 ug/l was significantly often found in the subgroup of patients with the EF improvement less than 10% or worsening and with significant left ventricular dilatation during 6 months follow-up. Cardiac catheterization itself does not affect collagen metabolism. Conclusion: We concluded that collagen metabolism markers enable to study in vivo the MI healing and to predict left ventricular functional and volume changes. 相似文献
994.
Jarid1b targets genes regulating development and is involved in neural differentiation 总被引:1,自引:0,他引:1
Schmitz SU Albert M Malatesta M Morey L Johansen JV Bak M Tommerup N Abarrategui I Helin K 《The EMBO journal》2011,30(22):4586-4600
995.
The effect of arbuscular mycorrhiza (AM) on the interaction of large plants and seedlings in an early succession situation
was investigated in a greenhouse experiment using compartmented rhizoboxes. Tripleurospermum inodorum, a highly mycorrhiza-responsive early coloniser of spoil banks, was cultivated either non-mycorrhizal or inoculated with
AM fungi in the central compartment of the rhizoboxes. After two months, seedlings of T. inodorum or Sisymbrium loeselii, a non-host species colonising spoil banks simultaneously with T. inodorum, were planted in lateral compartments, which were colonised by the extraradical mycelium (ERM) of the pre-cultivated T. inodorum in the inoculated treatments. The experiment comprised the comparison of two AM fungal isolates and two substrates: spoil
bank soil and a mixture of this soil with sand. As expected based on the low nutrient levels in the substrates, the pre-cultivated
T. inodorum plants responded positively to mycorrhiza, the response being more pronounced in phosphorus uptake than in nitrogen uptake
and growth. In contrast, the growth of the seedlings, both the host and the non-host species, was inhibited in the mycorrhizal
treatments. Based on the phosphorus and nitrogen concentrations in the biomass of the experimental plants, this growth inhibition
was attributed to nitrogen depletion in the lateral compartments by the ERM radiating from the central compartment. The results
point to an important aspect of mycorrhizal effects on the coexistence of large plants and seedlings in nutrient deficient
substrates. 相似文献
996.
Chaetosphaeria tortuosa is described as the newly discovered teleomorph of Menispora tortuosa, based on specimens from Canada and the Czech Republic, and single spore isolations from both morphs. The fungus produces superficial, more or less globose, papillate, dark brown to black smooth perithecia (200–)220–250 × (220–)230–260 μm. The asci are unitunicate, 8-spored, cylindrical-fusiform, (110–)120–133(–145) × 12–14 with a distinct apical, nonamyloid annulus 1–1.5 μm high, 3.5–4 μm wide. The ascospores are fusiform, 19–24 × 5–6 μm, hyaline, 3-septate, smooth, and 2-seriate in the ascus. The morphology of the teleomorph and anamorph are similar to that of C. ovoidea (anamorph: M. glauca), differing in dimensions of asci and ascospores, and in the disposition and morphology of the phialides of the anamorphs. The generic concept and phylogeny of Menispora is briefly discussed, and a key to the 11 species currently accepted in the genus is provided. 相似文献
997.
Glycine transporters are members of the Na+/Cl− dependent transporter gene family and play crucial roles in regulating inhibitory as well as excitatory neurotransmission.
In this report we show that calcium elevation in spinal cord synaptosomes decreases the levels of glycine transporter, GlyT1,
N-terminal immunoreactivity, and that this decrease can be blocked by calpain inhibitor. Sequencing of GST fusion proteins
containing the N-terminal domains of GlyT1A and B splice variants cleaved with rat recombinant calpain identified calpain
cleavage sites after glycine 17 in GlyT1B and N-terminally of the first conserved arginine residue in both GlyT1A and GlyT1B.
Expression in HEK293 cells revealed that truncation of the N-terminus of GlyT1 results in significant inhibition of glycine
uptake. A syntaxin1A GST fusion protein was able to pull-down N-terminally deleted GlyT1, indicating that calpain cleavage
does not eliminate syntaxin1A binding. These results suggest that calpain cleavage may regulate the transport activity/turnover
of GlyT1 in vivo by cleaving its N-terminal domain. 相似文献
998.
4-nitrophenyl 3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha- and beta-D-mannopyranosides were prepared from methyl 4,6-O-benzylidene-alpha-D-glucopyranoside and 1,3,4,6-tetra-O-acetyl-alpha-D-glucopyranose, respectively. Chemoselective reduction of both azides with hydrogen sulfide readily afforded 4-nitrophenyl 2-acetamido-4,6-di-O-acetyl-2-deoxy-alpha-D- and -beta-D-mannopyranosides in higher yields than reduction with triphenylphosphine or a polymer-supported triarylphosphine. Subsequent de-O-acetylation yielded 4-nitrophenyl 2-acetamido-2-deoxy-alpha-D-mannopyranoside and 4-nitrophenyl 2-acetamido-2-deoxy-beta-D-mannopyranoside in 20% and 44% overall yields, respectively. 相似文献
999.
Ulrike Treier Sabine Fuchs Martina Weber Warren W. Wakarchuk Christoph F. Beck 《Archives of microbiology》1989,152(6):572-577
Gametes of Chlamydomonas reinhardtii synthesize numerous proteins not observed in vegetative cells and vice versa. Gametogenesis induced changes in gene expression were confirmed by SDS-PAGE of in vitro translation products using total RNA from gametes and vegetative cells. Vegetative cells and gametes thus represent two cell types with distinct patterns of gene expression. The generation of mature gametes from liquid cultures of asynchronously growing vegetative cells was dependent on light. This light requirement could not be substituted for by an organic source of energy and carbon, indicating that light serves as a signal in gametogenesis. The light signal was shown to become effective only after preincubation in nitrogen-free medium. This delayed competence for light indicates that the two external signals — nitrogen-starvation and light —may function in sequence. Execution of the light dependent step in gamete formation required cytoplasmic protein synthesis and RNA synthesis.Abbreviations CAM
chloramphenicol
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- PSII
photosystem II
- TAP
Tris acetate phosphate
- TMP
Tris minimal phosphate
This paper is dedicated by C. F. Beck to Professor John L. Ingraham, teacher and friend, on the occasion of his 65th birthday 相似文献
1000.
Leaves ofNerium oleander L. plants, which had been previously kept in a shaded glasshouse for at least two months, were fed 1 mM dithiothreitol (DTT)
through their petioles, either for 12h in darkness (overnight) or for 2h in low light (28 μmol photons·m−2·s−1), in each case followed by a 3-h exposure to high light (1260 μmol photons·m−2·s−1). During exposure to high light, violaxanthin became converted to zeaxanthin in control leaves, to which water had been fed,
whereas zeaxanthin did not accumulate in leaves treated with DTT. Total carbon gain was not reduced by DTT during the photoinhibitory
treatment. Exposure to high light led to a decrease in the photochemical efficiency of photosystem II, measured as the ratio
of variable over maximum fluorescence emission,F
v/F
M, at both 298 K and 77K. The decrease was much more pronounced in the presence of DTT, mainly owing to a sustained increase
in the instantaneous fluorescence,F
o. By contrast, in the control leaves,F
o determined immediately after the high-light treatment showed a transient decrease below theF
o value obtained before the onset of the photoinhibitory treatment (i.e. after 12 h dark adaptation), followed by a rapid return
(within seconds) to this original level ofF
o during the following recovery period in darkness. Incubation of leaves with DTT led to large, sustained decreases in the
photon-use efficiency of photosynthetic O2 evolution by bright light, whilst the capacity of photosynthetic O2 evolution at light and CO2 saturation was less affected. In the control leaves, only small reductions in the photon yield and in the photosynthetic
capacity were observed. These findings are consistent with previous suggestions that zeaxanthin, formed in the xanthophyll
cycle by de-epoxidation of violaxanthin, is involved in protecting the photosynthetic apparatus against the adverse effects
of excessive light. 相似文献