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81.
Habermann FA André S Kaltner H Kübler D Sinowatz F Gabius HJ 《Histochemistry and cell biology》2011,135(6):539-552
Gene divergence has given rise to the galectin family of mammalian lectins. Since selective binding to distinct β-galactosides
underlies the known bioactivities of galectins, they could find application in cyto- and histochemistry. The pertinent question
on the characteristics of their individual reactivity profiles therefore needs to be answered. Toward this end, comparative
studies of a panel of galectins in defined systems are required. We here characterise the staining profiles of seven human
lectins as well as five natural derivatives originating from proteolytic truncation and serine phosphorylation and one engineered
variant. As test system, bovine germinal vesicle oocytes with their glycoprotein envelope (zona pellucida), which presents
bi- to tetraantennary complex-type N-glycans with N-acetyllactosamine repeats and core fucosylation, were processed. Technically, confocal laser scanning microscopy was used,
first with plant lectins to map the sialylation status. Hereby, α2,3/6-sialylation was detected in the superficial filamentous
meshwork of the zona pellucida, while sialic acid-free glycan chains were found to characterise the main inner part of the
compact layer of the zona pellucida. Galectin staining was specific and non-uniform. Significant differences in reactivity
were detected for the superficial filamentous meshwork and the compact layer of the zona pellucida between galectins-1 to
-4 versus galectins-8 and -9. The typical staining profiles intimate a spatially organised display of N-glycans in the different layers of the zona pellucida, underscoring the potential of galectins as cyto- and histochemical
tools. Our results encourage further comparative analysis and research to trace the underlying structural and/or topological
properties. 相似文献
82.
Many investigators have performed studies on specific defect situations or determined the contribution on isolated structures. Investigating the contribution of functional structures requires obtaining the kinematic response directly on spinal segments. The purpose of this study was to quantify the function of anatomical components on lumbar segments for different loading magnitudes. Eight spinal segments (L4-5) with a median age of 52 years (ranging from 38 to 59 years) and a low degree of disc degeneration were utilized for the in vitro testing. Specimens were mounted in a custom-built spine tester and loaded with pure moments (1-10 N m) to move within three anatomical planes at a loading rate of 1.0 degrees /s. Anatomy was successively reduced by: ligaments, facet capsules, joints and nucleus. Data were evaluated for range of motion, neutral zone and lordosis angle. Transection of posterior ligaments predominantly increased specimen flexion for all bending moments applied. Supraspinous ligament also indicated to resist in extension slightly, whereas the facet capsules did not. Facet joints contributed to axial rotation, but not in lateral bending. The anterior longitudinal ligament was found to slightly resist in axial rotation, but strongly in extension. Nucleotomy caused largest increase of all movements. The unloaded posture of the specimens changed after ligament dissection, indicating ligament pretension. The region of lumbar spine is interesting for finite element (FE) simulation due to the high evidence of disc degeneration and injuries. This study may help to understand the function of specific anatomical structures and assists in FE model calibration. We suggest to start a calibration procedure for such models with the smallest functional structure (annulus) and to cumulatively add further structures. 相似文献
83.
Genetic structures of the CIMMYT international yield trial targeted to irrigated environments 总被引:1,自引:0,他引:1
Susanne Dreisigacker Hailemichael Shewayrga Jose Crossa Vivi N. Arief Ian H. DeLacy Ravi P. Singh Mark J. Dieters Hans-Joachim Braun 《Molecular breeding : new strategies in plant improvement》2012,29(2):529-541
International yield trials are assembled by CIMMYT to disseminate promising wheat breeding materials worldwide. To assess
the genomic structure and linkage disequilibrium (LD) within this germplasm, wheat lines disseminated during 25 years of the
Elite Spring Wheat Yield Trial (ESWYT) targeted for irrigated environments of the world were genotyped with the high-throughput
Diversity Arrays Technology (DArT) marker system. Analyses of population structure assigned the ESWYT germplasm into five
major sub-populations that are shaped by prominent CIMMYT wheat lines and their descendants. Based on genetic distance, we
concluded that a constant level of genetic diversity was maintained over the years of ESWYT dissemination. Genetic distance
between the individual ESWYT lines significantly increased when the ESWYT were grouped according to the differences in years
of ESWYT dissemination, suggesting a systematic change in allele frequencies over time, most probably due to breeding and
directional selection. By means of multiple regression analyses, 78 markers displaying a significant change in allele frequency
across years were identified and interpreted as an indicator for constant selection. The markers identified were partly associated
with grain yield, leaf, stem, and yellow rust and point to key genomic regions for further investigation. Large numbers of
adjacent DArT marker pairs showed significant LD across the ESWYT population and within each of the five sub-populations identified.
Sub-population differentiation measured by the fixation index and average genetic distance were highly correlated with LD
levels, suggesting that the sub-populations themselves explain much of the LD. 相似文献
84.
Elongation factor (EF) Tu alternates between two interaction partners, EF-Ts and the ribosome, during its functional cycle.
On the ribosome, the interaction involves, among others, ribosomal protein L7/12. Here we compare EF-Ts and L7/12 with respect
to the conservation of sequence and structure. There is significant conservation of functionally important residues in the
N-terminal domain of EF-Ts and in the C-terminal domain of L7/12. The structure alignment based on the crystal structures
of the two domains suggests a high degree of similarity between the αA–βD–αB motif in L7/12 and the h1–turn–h2 motif in EF-Ts
which defines a common structural motif. The motif is remarkably similar with respect to fold, bulkiness, and charge distribution
of the solution surface, suggesting that it has a common function in binding EF-Tu.
Received: 12 June 2000 / Accepted: 10 October 2000 相似文献
85.
Plant-pollinator networks are systems of outstanding ecological and economic importance. A particularly intriguing aspect of these systems is their high diversity. However, earlier studies have concluded that the specific mechanisms of plant-pollinator interactions are destabilizing and should lead to a loss of diversity. Here we present a mechanistic model of plant and pollinator population dynamics with the ability to represent a broad spectrum of interaction structures. Using this model, we examined the influence of pollinators on the stability of a plant community and the relationship between pollinator specialization and stability. In accordance with earlier work, our results show that plant-pollinator interactions may severely destabilize plant coexistence, regardless of the degree of pollinator specialization. However, if plant niche differentiation, a classical stabilizing mechanism, is sufficiently strong to overcome the minority disadvantage with respect to pollination, interactions with pollinators may even increase the stability of a plant community. In addition to plant niche differentiation, the relationship between specialization and stability depends on a number of parameters that affect pollinator growth rates. Our results highlight the complex effects of this particular type of mutualism on community stability and call for further investigations of the mechanisms of diversity maintenance in plant-pollinator systems. 相似文献
86.
Saussez S Nonclercq D Laurent G Wattiez R André S Kaltner H Gabius HJ Kiss R Toubeau G 《Histochemistry and cell biology》2005,123(1):29-41
The current study focused on galectins (-1, -3, -4, -7, and –8) and deliberately performed immunohistochemical fingerprinting to explore their complexity in a context of experimental renal carcinogenesis. The diethylstilbestrol (DES)-induced renal tumors in male Syrian hamster kidney (SHKT) represent a unique animal model for the study of estrogen-dependent renal malignancies. Kidney sections of DES-treated hamsters (3 days to 11 months of DES exposure) were analyzed by immunohistochemistry using a panel of non-crossreactive antibodies raised against galectins-1, -3, -4, -7, and -8. Levels of expression were quantitatively determined by using computer-assisted microscopy on immunostained tissue sections. Except for galectin-4, all above mentioned galectins were expressed in kidney tumors. Small clusters of galectin-1-positive, most likely preneoplastic cells at the corticomedullary junction were already evident 1 week after DES administration. Galectin-1 and -3 expression was apparently associated with the first steps of the neoplastic transformation, because small tumorous buds were found to be positive after 1 month of treatment. In contrast, galectins-7 and -8 were detected in large tumors and medium-sized tumors, respectively, thereby indicating an involvement in later stages of DES-induced SHKT. Galectins-1, -3, -7, and -8 were also detected by immunofluorescence staining in the HKT-1097 cell line established from SHKT, thus illustrating the stability of galectin expression in tumor cells. Our data document the presence and differential regulation of galectins in the course of renal tumorigenesis in the model of DES-induced SHKT. 相似文献
87.
Matthias Kirsch Mustafa B. A. Djamgoz Hans-Joachim Wagner 《Cell and tissue research》1990,260(1):123-130
Summary A negative feedback interaction between luminosity type horizonatal cells (HCs) and green-sensitive cones generates the long-wavelength-sensitive depolarizing response in biphasic chromaticity type HCs. This interaction is suppressed in the dark and is potentiated by light adaptation of the retina. HCs are morphologically plastic; during light adaptation, their dendritic terminals within cone pedicles extend, giving rise to spinules. This paper examines whether there is a quantitative correlation between the time course of light-dependent formation of the spinules and enhancement of the feedback interaction. The strength of the feedback interaction in isolated retinac of the roach was determined as the neutral wavelength at which reversal of spectral response polarity occurred in biphasic HCs. A good correlation was found between the neutral wavelength and the spinule/ribbon ratios of retinae. Biphasic HCs were intracellularly stained with horseradish peroxidase and the correlative ultrastructure of the contacted pedicles was examined. Neutral wavelength was found to be correlated with the spinule number, weighted according to the number of synaptic contacts mediating feed-forward transmission. The latter was estimated from the total number of labelled Cb/H2 HC processes (central and lateral) at synaptic triads. A model in which spinules mediate the negative feedback interaction of HCs in the retina of cyprinid fish is presented. 相似文献
88.
The interaction between Urtica dioica agglutinin (UDA) and N-acetylglucosamine (GlcNAc) and its (1-4)-linked oligomers was studied by fluorescence titration and isothermal titration microcalorimetry. UDA possesses one significant binding site that can be measured calorimetrically. This site is composed of three subsites, each subsite accommodating one GlcNAc residue. The interaction is enthalpically driven, and the binding area of UDA is characterized by a H of interaction for a given oligosaccharide considerably smaller than that of wheat germ agglutinin (WGA), despite the fact that they both belong to a family of proteins composed entirely of hevein domains. Relatively high Cp values of the UDA-carbohydrate interactions and more favorable entropy term compared to WGA suggest that binding of the carbohydrate ligands by UDA has a higher hydrophobic component than that of WGA. 相似文献
89.
Metabolism of naphthalene by the biphenyl-degrading bacterium Pseudomonas paucimobilis Q1 总被引:7,自引:0,他引:7
Pseudomonas paucimobilis Q1 originally isolated as biphenyl degrading organism (Furukawa et al. 1983), was shown to grow with naphthalene. After growth with biphenyl or naphthalene the strain synthesized the same enzyme for the ring cleavage of 2,3-dihydroxybiphenyl or 1,2-dihydroxynaphthalene. The enzyme, although characterized as 2,3-dihydroxybiphenyl dioxygenase (Taira et al. 1988), exhibited considerably higher relative activity with 1,2-dihydroxynaphthalene. These results demonstrate that this enzyme can function both in the naphthalene and biphenyl degradative pathway.Abbreviations DHBP
dihydroxybiphenyl
- DHBPDO
2,3-dihydroxybiphenyl dioxygenase
- DHDHNDH
1,2-dihydroxy-1,2-dihydronaphthalene dehydrogenase
- DHN
1,2-dihydroxynaphthalene
- DHNDO
1,2-dihydroxynaphthalene dioxygenase
- HBP
cis-2-hydroxybenzalpyruvate
- HOPDA
2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate
- PCB
polychlorinated biphenyl
- 2NS
naphthalene-2-sulfonic acid 相似文献
90.
Bilateral damage of the medial temporal lobe system prevents the formation of new declarative memories but leaves intact knowledge that was acquired before damage. For motor learning, no structure has been identified that plays a comparable role for the consolidation of motor memories. The deficits of motor learning are focal and show a similar allocation to the various of motor learning are focal and show a similar allocation to the various sensorimotor subsystems, as do the corresponding non-mnemonic functions. The involvement of sensorimotor circuitries changes during motor learning so that association areas are preferentially activated in the early stages, and cerebello- and striato-motor-cortical loops are preferentially activated in the late stages of motor learning. Recent neuroanatomical and neurophysiological findings on the effects of brain lesions in human and non-human primates are discussed. 相似文献