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111.
Bernd-Ulrich Meyburg Christiane Meyburg Florian Franck-Neumann 《Journal of Ornithology》2007,148(2):157-166
There is very little confirmed information on the social organisation of breeding Lesser Spotted Eagle populations, the turnover
rate of adults, and their nest-site and partner fidelity. According to established knowledge, however, breeding individuals
are territorial and defend at least the immediate vicinity of the nest site against their own species. It has further been
thought that females rearing young, as with the females of other raptor species, remain within a radius of only a few kilometres
of their eyrie. Using GPS satellite telemetry and DNA microsatellite analysis (DNA STR typing), we were able to disprove this
prevailing hypothesis. A satellite-tracked female flew over 50 km away from her eyrie (D) in at least two different directions
and visited at least one other occupied eyrie (T). It was also established that at least two strange females arrived at her
eyrie, which contained young, from as far away as 57 km, and probably remained there for some considerable time. The pool
of alleles represented at the different loci analysed, as well as the distribution of these alleles among the individuals,
excludes the possibility that these females could be sisters or even half-sisters. Visits of strange eagles at this eyrie
were also confirmed by direct observation. It can therefore be assumed that males only exhibit territorial behaviour towards
their own sex and not towards strange females and that females do not exhibit territorial behaviour towards other females;
but all these assumptions must be confirmed by further studies. For the first time it could be proved by means of microsatellite
analysis that almost all females studied used the same breeding site for 2 consecutive years. The longest established period
in which both partners of a pair remained at the same breeding site was 3 consecutive years. 相似文献
112.
Schneider JC El Kebir D Chéreau C Lanone S Huang XL De Buys Roessingh AS Mercier JC Dall'Ava-Santucci J Dinh-Xuan AT 《American journal of physiology. Heart and circulatory physiology》2003,284(6):H2311-H2319
Nitric oxide (NO) is synthesized from l-arginine by the Ca(2+)/calmodulin-sensitive endothelial NO synthase (NOS) isoform (eNOS). The present study assesses the role of Ca(2+)/calmodulin-dependent protein kinase II (CaMK II) in endothelium-dependent relaxation and NO synthesis. The effects of three CaMK II inhibitors were investigated in endothelium-intact aortic rings of normotensive rats. NO synthesis was assessed by a NO sensor and chemiluminescence in culture medium of cultured porcine aortic endothelial cells stimulated with the Ca(2+) ionophore A23187 and thapsigargin. Rat aortic endothelial NOS activity was measured by the conversion of l-[(3)H]arginine to l-[(3)H]citrulline. Three CaMK II inhibitors, polypeptide 281-302, KN-93, and lavendustin C, attenuated the endothelium-dependent relaxation of endothelium-intact rat aortic rings in response to acetylcholine, A23187, and thapsigargin. None of the CaMK II inhibitors affected the relaxation induced by NO donors. In a porcine aortic endothelial cell line, KN-93 decreased NO synthesis and caused a rightward shift of the concentration-response curves to A23187 and thapsigargin. In rat aortic endothelial cells, KN-93 significantly decreased bradykinin-induced eNOS activity. These results suggest that CaMK II was involved in NO synthesis as a result of Ca(2+)-dependent activation of eNOS. 相似文献
113.
The reticulon and DP1/Yop1p proteins form immobile oligomers in the tubular endoplasmic reticulum 总被引:2,自引:0,他引:2
Shibata Y Voss C Rist JM Hu J Rapoport TA Prinz WA Voeltz GK 《The Journal of biological chemistry》2008,283(27):18892-18904
We recently identified a class of membrane proteins, the reticulons and DP1/Yop1p, which shape the tubular endoplasmic reticulum (ER) in yeast and mammalian cells. These proteins are highly enriched in the tubular portions of the ER and virtually excluded from other regions. To understand how they promote tubule formation, we characterized their behavior in cellular membranes and addressed how their localization in the ER is determined. Using fluorescence recovery after photobleaching, we found that yeast Rtn1p and Yop1p are less mobile in the membrane than normal ER proteins. Sucrose gradient centrifugation and cross-linking analyses show that they form oligomers. Mutants of yeast Rtn1p, which no longer localize exclusively to the tubular ER or are even totally inactive in inducing ER tubules, are more mobile and oligomerize less extensively. The mammalian reticulons and DP1 are also relatively immobile and can form oligomers. The conserved reticulon homology domain that includes the two membrane-embedded segments is sufficient for the localization of the reticulons to the tubular ER, as well as for their diffusional immobility and oligomerization. Finally, ATP depletion in both yeast and mammalian cells further decreases the mobilities of the reticulons and DP1. We propose that oligomerization of the reticulons and DP1/Yop1p is important for both their localization to the tubular domains of the ER and for their ability to form tubules. 相似文献
114.
Rutkowska A Mayer MP Hoffmann A Merz F Zachmann-Brand B Schaffitzel C Ban N Deuerling E Bukau B 《The Journal of biological chemistry》2008,283(7):4124-4132
In all organisms ribosome-associated chaperones assist early steps of protein folding. To elucidate the mechanism of their action, we determined the kinetics of individual steps of the ribosome binding/release cycle of bacterial trigger factor (TF), using fluorescently labeled chaperone and ribosome-nascent chain complexes. Both the association and dissociation rates of TF-ribosome complexes are modulated by nascent chains, whereby their length, sequence, and folding status are influencing parameters. However, the effect of the folding status is modest, indicating that TF can bind small globular domains and accommodate them within its substrate binding cavity. In general, the presence of a nascent chain causes an up to 9-fold increase in the rate of TF association, which provides a kinetic explanation for the observed ability of TF to efficiently compete with other cytosolic chaperones for binding to nascent chains. Furthermore, a subset of longer nascent polypeptides promotes the stabilization of TF-ribosome complexes, which increases the half-life of these complexes from 15 to 50 s. Nascent chains thus regulate their folding environment generated by ribosome-associated chaperones. 相似文献
115.
Pivneva T Haas B Reyes-Haro D Laube G Veh RW Nolte C Skibo G Kettenmann H 《Cell calcium》2008,43(6):591-601
Ca(2+) signaling is the astrocyte form of excitability and the endoplasmic reticulum (ER) plays an important role as an intracellular Ca(2+) store. Since the subcellular distribution of the ER influences Ca(2+) signaling, we compared the arrangement of ER in astrocytes of hippocampus tissue and astrocytes in cell culture by electron microscopy. While the ER was usually located in close apposition to the plasma membrane in astrocytes in situ, the ER in cultured astrocytes was close to the nuclear membrane. Activation of metabotropic receptors linked to release of Ca(2+) from ER stores triggered distinct responses in cultured and in situ astrocytes. In culture, Ca(2+) signals were commonly first recorded close to the nucleus and with a delay at peripheral regions of the cells. Store-operated Ca(2+) entry (SOC) as a route to refill the Ca(2+) stores could be easily identified in cultured astrocytes as the Zn(2+)-sensitive component of the Ca(2+) signal. In contrast, such a Zn(2+)-sensitive component was not recorded in astrocytes from hippocampal slices despite of evidence for SOC. Our data indicate that both, astrocytes in situ and in vitro express SOC necessary to refill stores, but that a SOC-related signal is not recorded in the cytoplasm of astrocytes in situ since the stores are close to the plasma membrane and the refill does not affect cytoplasmic Ca(2+) levels. 相似文献
116.
Meryl Hassan Claire El Yazidi Christiane Malezet-Desmoulins Marie-Josèphe Amiot Alain Margotat 《The Journal of nutritional biochemistry》2010,21(7):645-652
Adipocyte dysfunction plays a major role in the outcome of obesity, insulin resistance and related cardiovascular complications. Thus, considerable efforts are underway in the pharmaceutical industry to find molecules that target the now well-documented pleiotropic functions of adipocyte. We previously reported that the dietary flavonoid phloretin enhances 3T3-L1 adipocyte differentiation and adiponectin expression at least in part through PPARγ activation. The present study was designed to further characterize the molecular mechanisms underlying the phloretin-mediated effects on 3T3-L1 adipocytes using microarray technology. We show that phloretin positively regulates the expression of numerous genes involved in lipogenesis and triglyceride storage, including GLUT4, ACSL1, PEPCK1, lipin-1 and perilipin (more than twofold). The expression of several genes encoding adipokines, in addition to adiponectin and its receptor, is positively or negatively regulated in a way that suggests a possible reduction in systemic insulin resistance and obesity-associated inflammation. Improvement of insulin sensitivity is also suggested by the overexpression of genes associated with insulin signal transduction, such as CAP, PDK1 and Akt2. Many of these genes are PPARγ targets, confirming the involvement of PPARγ pathway in the phloretin effects on adipocytes. In light of these microarray data, it is reasonable to assume that phloretin may be beneficial for reducing insulin resistance, in a similar way to the thiazolidinedione class of antidiabetic drugs. 相似文献
117.
Bayesian Modeling of the Yeast SH3 Domain Interactome Predicts Spatiotemporal Dynamics of Endocytosis Proteins 下载免费PDF全文
Raffi Tonikian Xiaofeng Xin Christopher P. Toret David Gfeller Christiane Landgraf Simona Panni Serena Paoluzi Luisa Castagnoli Bridget Currell Somasekar Seshagiri Haiyuan Yu Barbara Winsor Marc Vidal Mark B. Gerstein Gary D. Bader Rudolf Volkmer Gianni Cesareni David G. Drubin Philip M. Kim Sachdev S. Sidhu Charles Boone 《PLoS biology》2009,7(10)
SH3 domains are peptide recognition modules that mediate the assembly of diverse biological complexes. We scanned billions of phage-displayed peptides to map the binding specificities of the SH3 domain family in the budding yeast, Saccharomyces cerevisiae. Although most of the SH3 domains fall into the canonical classes I and II, each domain utilizes distinct features of its cognate ligands to achieve binding selectivity. Furthermore, we uncovered several SH3 domains with specificity profiles that clearly deviate from the two canonical classes. In conjunction with phage display, we used yeast two-hybrid and peptide array screening to independently identify SH3 domain binding partners. The results from the three complementary techniques were integrated using a Bayesian algorithm to generate a high-confidence yeast SH3 domain interaction map. The interaction map was enriched for proteins involved in endocytosis, revealing a set of SH3-mediated interactions that underlie formation of protein complexes essential to this biological pathway. We used the SH3 domain interaction network to predict the dynamic localization of several previously uncharacterized endocytic proteins, and our analysis suggests a novel role for the SH3 domains of Lsb3p and Lsb4p as hubs that recruit and assemble several endocytic complexes. 相似文献
118.
Christiane Liers Ren Ullrich Marek Pecyna Dietmar Schlosser Martin Hofrichter 《Enzyme and microbial technology》2007,41(6-7):785-793
The hard wood-colonizing ascomycete Xylaria polymorpha, that is seemingly lacking peroxidases, produces laccase as sole ligninolytic oxidoreductase. The fungus secreted the enzyme preferably during the growth in complex media based on tomato juice. Addition of 2,5-xylidine considerably stimulated laccase production (up to 14,000 U l−1). The enzyme was purified to homogeneity by anion exchange and size exclusion chromatography and characterized by biochemical and molecular methods. Xylaria laccase has a molecular mass of 67 kDa, a pI of 3.1 and an absorption maximum at 605 nm that is characteristic for blue copper proteins. It oxidized all typical laccase substrates including ABTS, 2,6-dimethoxyphenol, guaiacol as well as syringaldazine (catalytic efficiencies 3 × 103 to 7 × 104 M−1 s−1). The deduced amino acid sequence of one amplified laccase gene sequence between the copper binding regions 1 and 3 showed a high level of identity to some other laccases from ascomycetes. Furthermore, the sequence of an internal peptide fragment of the purified laccase was identical with an amino acid sequence deduced from the nucleotide sequence of the laccase gene. Xylaria laccase was found to oxidize a non-phenolic β-O-4 lignin model compound in presence of 1-hydroxybenzotriazole into the corresponding keto-form. The results of this study show that – in addition to ligninolytic basidiomycetes – also wood-dwelling ascomycetes can produce high titers of laccase that may be involved in the oxidation of lignin. 相似文献
119.
Karelle Benardais Basem Kasem Alice Couegnas Brigitte Samama Sebastien Fernandez Christiane Schaeffer Maria-Cristina Antal Didier Job Annie Schweitzer Annie Andrieux Anne Giersch Astrid Nehlig Nelly Boehm 《PloS one》2010,5(9)