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11.
Gene and domain duplication in the chordate Otx gene family: insights from amphioxus Otx 总被引:6,自引:1,他引:5
We report the genomic organization and deduced protein sequence of a
cephalochordate member of the Otx homeobox gene family (AmphiOtx) and show
its probable single-copy state in the genome. We also present molecular
phylogenetic analysis indicating that there was single ancestral Otx gene
in the first chordates which was duplicated in the vertebrate lineage after
it had split from the lineage leading to the cephalochordates. Duplication
of a C-terminal protein domain has occurred specifically in the vertebrate
lineage, strengthening the case for a single Otx gene in an ancestral
chordate whose gene structure has been retained in an extant
cephalochordate. Comparative analysis of protein sequences and published
gene expression patterns suggest that the ancestral chordate Otx gene had
roles in patterning the anterior mesendoderm and central nervous system.
These roles were elaborated following Otx gene duplication in vertebrates,
accompanied by regulatory and structural divergence, particularly of Otx1
descendant genes.
相似文献
12.
Premelting at the surface of ice crystals is caused by factors such as temperature, radius of curvature, and solute composition. When polycrystalline ice samples are warmed from well below the equilibrium melting point, surface melting may begin at temperatures as low as -15 degrees C. However, it has been reported (. Biophys. J. 65:1853-1865) that when polycrystalline ice was warmed in a differential scanning calorimetry (DSC) pan, melting began at about -50 degrees C, this extreme behavior being attributed to short-range forces. We show that there is no driving force for such premelting, and that for pure water samples in DSC pans curvature effects will cause premelting typically at just a few degrees below the equilibrium melting point. We also show that the rate of warming affects the slope of the DSC baseline and that this might be incorrectly interpreted as an endotherm. The work has consequences for DSC operators who use water as a standard in systems where subfreezing runs are important. 相似文献
13.
IB Masters MM Eastburn PW Francis R Wootton PV Zimmerman RS Ware AB Chang 《Respiratory research》2005,6(1):16
Background
Flexible video bronchoscopes, in particular the Olympus BF Type 3C160, are commonly used in pediatric respiratory medicine. There is no data on the magnification and distortion effects of these bronchoscopes yet important clinical decisions are made from the images. The aim of this study was to systematically describe the magnification and distortion of flexible bronchoscope images taken at various distances from the object.Methods
Using images of known objects and processing these by digital video and computer programs both magnification and distortion scales were derived.Results
Magnification changes as a linear function between 100 mm (×1) and 10 mm (×9.55) and then as an exponential function between 10 mm and 3 mm (×40) from the object. Magnification depends on the axis of orientation of the object to the optic axis or geometrical axis of the bronchoscope. Magnification also varies across the field of view with the central magnification being 39% greater than at the periphery of the field of view at 15 mm from the object. However, in the paediatric situation the diameter of the orifices is usually less than 10 mm and thus this limits the exposure to these peripheral limits of magnification reduction. Intraclass correlations for measurements and repeatability studies between instruments are very high, r = 0.96. Distortion occurs as both barrel and geometric types but both types are heterogeneous across the field of view. Distortion of geometric type ranges up to 30% at 3 mm from the object but may be as low as 5% depending on the position of the object in relation to the optic axis.Conclusion
We conclude that the optimal working distance range is between 40 and 10 mm from the object. However the clinician should be cognisant of both variations in magnification and distortion in clinical judgements. 相似文献14.
Quercetin glucuronides are the main circulating metabolites of quercetin in humans. We hypothesise that the potential availability of the aglycone within tissues depends on the substrate specificity of the deconjugating enzyme beta-glucuronidase towards circulating flavonoid glucuronides. Human tissues (small intestine, liver and neutrophils) exhibited beta-glucuronidase against quercetin glucuronides. The various quercetin glucuronides were deconjugated at similar rates, but liver cell-free extracts were the most efficient and the activity was completely inhibited by saccharo-1,4-lactone (a beta-glucuronidase inhibitor). Furthermore, pure recombinant human beta-glucuronidase hydrolysed various flavonoid glucuronides, with a 20-fold variation in catalytic efficiency (k(cat)/K(m)=1.3x10(3) M(-1) s(-1) for equol-7-O-glucuronide and 26x10(3) M(-1) s(-1) for kaempferol-3-O-glucuronide). Similar catalytic efficiencies were obtained for quercetin O-glucuronides substituted at different positions. These results show that flavonoid glucuronides can be deconjugated by microsomal beta-glucuronidase from various human cells. 相似文献
15.
16.
Ahilanandan Dushianthan Victoria Goss Rebecca Cusack Michael PW Grocott Anthony D Postle 《Respiratory research》2014,15(1)
Background
Acute respiratory distress syndrome (ARDS) is a life-threatening critical illness, characterised by qualitative and quantitative surfactant compositional changes associated with premature airway collapse, gas-exchange abnormalities and acute hypoxic respiratory failure. The underlying mechanisms for this dysregulation in surfactant metabolisms are not fully explored. Lack of therapeutic benefits from clinical trials, highlight the importance of detailed in-vivo analysis and characterisation of ARDS patients according to patterns of surfactant synthesis and metabolism.Methods
Ten patients with moderate to severe ARDS were recruited. Most (90%) suffered from pneumonia. They had an infusion of methyl-D9-choline chloride and small volume bronchoalveolar lavage fluid (BALF) was obtained at 0,6,12,24,48,72 and 96 hours. Controls were healthy volunteers, who had BALF at 24 and 48 hours after methyl-D9-choline infusion. Compositional analysis and enrichment patterns of stable isotope labelling of surfactant phosphatidylcholine (PC) was determined by electrospray ionisation mass spectrometry.Results
BALF of patients with ARDS consisted of diminished total PC and fractional PC16:0/16:0 concentrations compared to healthy controls. Compositional analysis revealed, reductions in fractional compositions of saturated PC species with elevated levels of longer acyl chain unsaturated PC species. Molecular specificity of newly synthesised PC fraction showed time course variation, with lower PC16:0/16:0 composition at earlier time points, but achieved near equilibrium with endogenous composition at 48 hours after methyl-D9-choline infusion. The enrichment of methyl-D9-choline into surfactant total PC is nearly doubled in patients, with considerable variation between individuals.Conclusions
This study demonstrate significant alterations in composition and kinetics of surfactant PC extracted from ARDS patients. This novel approach may facilitate biochemical phenotyping of ARDS patients according to surfactant synthesis and metabolism, enabling individualised treatment approaches for the management of ARDS patients in the future. 相似文献17.
18.
Syntheses of the title compounds — commonly known as ‘daidzein 7-glucuronide’ and ‘daidzein 4′,7-diglucuronide’ — are described. Selective 7-deacetylation of 4′,7-di-O-acetyldaidzein is employed. 相似文献
19.
Intrarectal transmission of simian immunodeficiency virus in rhesus macaques: selective amplification and host responses to transient or persistent viremia. 总被引:3,自引:3,他引:0
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P Trivedi D Horejsh S B Hinds I I Hinds PW M S Wu M S Salvato C D Pauza 《Journal of virology》1996,70(10):6876-6883
Intrarectal simian immunodeficiency virus (SIV) infection in rhesus macaques is a model for sexual transmission of primate retroviruses. Phylogenetic studies on envelope gene sequences that were present in blood following intrarectal SIV inoculation provided evidence for selective amplification of a subset of viruses present in the inoculum and defined one amino acid sequence uniquely associated with intrarectal infection. Both persistent and transient viremia states were observed after intrarectal infection. Immune responses in persistently infected animals accounted for slower rates of disease progression despite the presence of highly pathogenic viruses that were documented by transfusion studies. Transient viremia elicited protective immunity against subsequent intrarectal virus challenge but did not protect against intravenous virus challenge. Transient viremia usually but not always led to self-limiting infection. In one animal, we documented a relapse to active viremia long after the initial transient viremia. SIV transmission across mucosal barriers affects pathogenesis in the short term by limiting the types of viruses established in the host and in the longer term by establishing host responses that slow disease progression despite the presence of highly pathogenic viruses in blood. 相似文献
20.
We have re-examined the evidence against the phloem mobility of oligogalacturonide elicitors using a reduced oligogalacturonide
in the phloem translocation system ofRicinus communis var. Gibsonii. A tritium-labelled end-reduced oligogalacturonide of degree of polymerisation 6 was injected into the hollow
centre of the petiole of four- to five-week-old plants. Two experimental procedures were followed. In the first, the whole
plant was harvested and dissected after 5 h incubation. In the second, phloem sap was collected from an incision in the main
stem below the injected petiole; collection started 2 h after incubation and continued for a further 3 h. Determination of
the total radiolabel present in the dissected plant showed that at least 8% of the applied activity was exported from the
injected leaf, most of this being recovered from the main stem below the injected petiole and the roots. The activity in the
phloem exudate showed that the rate of export of radiolabel was already at its maximum by the end of the 2-h incubation period.
Radiolabelled material recovered from the main stem was found to be highly comparable to starting material when subjected
to thin-layer chromatography. These results demonstrate the phloem mobility of reduced oligogalacturonides of low degree of
polymerisation and therefore re-establish the potential for oligogalacturonides to act as systemic signals. 相似文献