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991.
Martínez-Barbosa ME Cammas-Marion S Bouteiller L Vauthier C Ponchel G 《Bioconjugate chemistry》2009,20(8):1490-1496
In the present work, the possibility to obtain PEGylated nanoparticles from two PBLG derivatives, PEG-b-poly(γ-benzyl L-glutamate), PBLG-PEG-60, and poly(γ-benzyl L-glutamate), PBLG-Bnz-50, by nanoprecipitation has been investigated. Particles were prepared not only from one polymer (PBLG-PEG-60 or PBLG-Bnz-50), but also from mixtures of two PBLG derivatives, PBLG-PEG-60 and PBLG-Bnz-50, in different ratios (90/10, 77/23, and 40/60 wt %). Because of the presence of PEG chains, hydrophilic particles were obtained, which was confirmed by ζ potential measurements (ζ from -13 mV and -21 mV) and by isothermal titration microcalorimetry (ITC). This last technique has shown no heat exchange when BSA was added to PEGylated nanoparticles. Further, complement activation has been evaluated by crossed immuno-electrophoresis demonstrating that the introduction of 77 wt % of PEGylated PBLG chains in the particles was enough to ensure a low complement activation activity. This effect was strongly correlated to the ζ potential of the particles, which decreased with an increase of PEG chains content. Interestingly, such properties are of interest for the preparation of degradable stealth nanocarriers. Moreover, it is suggested that the introduction of a reasonable amount (up to 20 wt %) of a second copolymer in the particle composition can be possible without modifying their stealth character. Moreover, the presence of this second copolymer would help to introduce a second functionality to the particles. 相似文献
992.
Sebastien Elis Elisabeth Blesbois Isabelle Couty Sandrine Balzergue Marie‐Laure Martin‐Magniette Florence Batellier Marina S. Govoroun 《Molecular reproduction and development》2009,76(11):1043-1055
Despite the regular decrease in fertility observed in hens, especially in “meat” lines, little is known about genes affecting fertility. We used the Affymetrix microarray to search for oocyte genes whose expression would vary in relation to fertility rate in both “laying” and “meat” line hens. We focused on oocyte genes because several of them have been found to be involved in fertility in other species. Based on microarray analysis, 54 and 84 genes were differentially expressed between germinal disc regions (GDR) of F1 maturation stage oocytes from hens exhibiting either high (100%) or low (from 22% to 80%) fertility rate from laying and meat lines respectively. Most of these differentially expressed genes were distributed between “laying” and “meat” lines indicating that mechanisms involved in the decrease in fertility rates in these two cases were independent. Real time RT‐PCR performed on the same samples which were used for microarray confirmed in several cases differences in gene expression levels detected by microarray. Moreover the correlations between gene expression levels and fertility rates were evaluated for the 10 most interesting genes at different stages of follicular maturation and early embryo development on individual GDR samples from hens exhibiting different fertility rates. In total, we identified five genes whose expression levels correlated with fertility rate in accordance with findings of microarray analysis and real time RT‐PCR: VWC2, CR407412, TAPA, FGL2, and TRAP6. The biological significance of these genes sheds light on potential mechanisms influencing fertility and could provide candidates for fertility markers in the hen. Mol. Reprod. Dev. 76: 1043–1055, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
993.
Lisa Miranda Anna Platek Marie-Agnès Gueuning Yurda Ozkan Louis Hue Mark H. Rider Sandrine Horman 《Biochemical and biophysical research communications》2010,396(3):656-219
AMP-activated protein kinase (AMPK), a known regulator of cellular and systemic energy balance, is now recognized to control cell division, cell polarity and cell migration, all of which depend on the actin cytoskeleton. Here we report the effects of A769662, a pharmacological activator of AMPK, on cytoskeletal organization and signalling in epithelial Madin-Darby canine kidney (MDCK) cells. We show that AMPK activation induced shortening or radiation of stress fibers, uncoupling from paxillin and predominance of cortical F-actin. In parallel, Rho-kinase downstream targets, namely myosin regulatory light chain and cofilin, were phosphorylated. These effects resembled the morphological changes in MDCK cells exposed to hyperosmotic shock, which led to Ca2+-dependent AMPK activation via calmodulin-dependent protein kinase kinase-β(CaMKKβ), a known upstream kinase of AMPK. Indeed, hypertonicity-induced AMPK activation was markedly reduced by the STO-609 CaMKKβ inhibitor, as was the increase in MLC and cofilin phosphorylation. We suggest that AMPK links osmotic stress to the reorganization of the actin cytoskeleton. 相似文献
994.
Songbirds are one of the few vertebrate groups (including humans) that evolved the ability to learn vocalizations. During song learning, social interactions with adult models are crucial and young songbirds raised without direct contacts with adults typically produce abnormal songs showing phonological and syntactical deficits. This raises the question of what functional representation of their vocalizations such deprived animals develop. Here we show that young starlings that we raised without any direct contact with adults not only failed to differentiate starlings' typical song classes in their vocalizations but also failed to develop differential neural responses to these songs. These deficits appear to be linked to a failure to acquire songs' functions and may provide a model for abnormal development of communicative skills, including speech. 相似文献
995.
Dessing MC Butter LM Teske GJ Claessen N van der Loos CM Vogl T Roth J van der Poll T Florquin S Leemans JC 《PloS one》2010,5(10):e13394
Background
Inflammation is commonly followed by the release of endogenous proteins called danger associated molecular patterns (DAMPs) that are able to warn the host for eminent danger. S100A8/A9 subunits are DAMPs that belong to the S100 family of calcium binding proteins. S100A8/A9 complexes induce an inflammatory response and their expression correlates with disease severity in several inflammatory disorders. S100A8/A9 promote endotoxin- and Escherichia (E.) coli-induced sepsis showing its contribution in systemic infection. The role of S100A8/A9 during a local infection of the urinary tract system caused by E. coli remains unknown.Methodology/Principal Findings
We investigated the contribution of S100A8/A9 in acute urinary tract infection (UTI) by instilling 2 different doses of uropathogenic E. coli transurethrally in wild type (WT) and S100A9 knockout (KO) mice. Subsequently, we determined bacterial outgrowth, neutrophilic infiltrate and inflammatory mediators in bladder and kidney 24 and 48 hours later. UTI resulted in a substantial increase of S100A8/A9 protein in bladder and kidney tissue of WT mice. S100A9 KO mice displayed similar bacterial load in bladder or kidney homogenate compared to WT mice using 2 different doses at 2 different time points. S100A9 deficiency had little effect on the inflammatory responses to E. Coli-induced UTI infection, as assessed by myeloperoxidase activity in bladder and kidneys, histopathologic analysis, and renal and bladder cytokine concentrations.Conclusions
We show that despite high S100A8/A9 expression in bladder and kidney tissue upon UTI, S100A8/A9 does not contribute to an effective host response against E. Coli in the urinary tract system. 相似文献996.
The way individuals pair to produce reproductive units is a major factor determining evolution. This process is complex because it is determined not only by individual mating preferences, but also by numerous other factors such as competition between mates. Consequently, preferred and actual characteristics of mates obtained should differ, but this has rarely been addressed. We simultaneously measured mating preferences for stature, body mass, and body mass index, and recorded corresponding actual partner's characteristics for 116 human couples from France. Results show that preferred and actual partner's characteristics differ for male judges, but not for females. In addition, while the correlation between all preferred and actual partner's characteristics appeared to be weak for female judges, it was strong for males: while men prefer women slimmer than their actual partner, those who prefer the slimmest women also have partners who are slimmer than average. This study therefore suggests that the influences of preferences on pair formation can be sex-specific. It also illustrates that this process can lead to unexpected results on the real influences of mating preferences: traits considered as highly influencing attractiveness do not necessarily have a strong influence on the actual pairing, the reverse being also possible. 相似文献
997.
Aim Understanding the processes that drive invasion success of alien species has received considerable attention in current ecological research. From an evolutionary point of view, many studies have shown that the phylogenetic similarity between the invader species and the members of the native community may be an important aspect of invasiveness. In this study, using a coarse‐scale systematic sampling grid of 1 km2, we explore whether the occupancy frequency of two groups of alien species, archaeophytes and neophytes, in the urban angiosperm flora of Brussels is influenced by their phylogenetic relatedness to native species. Location The city of Brussels (Belgium). Methods We used ordinary least‐squares regressions and quantile regressions for analysing the relationship between the occupancy frequency of alien species in the sampled grid and their phylogenetic distance to the native species pool. Results Alien species with high occupancy frequency in the sampled grid are, on average, more phylogenetically related to native species than are less frequent aliens, although this relationship is significant only for archaeophytes. In addition, as shown by the quantile regressions, the relationship between phylogenetic relatedness to the native flora and occupancy frequency is much stronger for the most frequent aliens than for rare aliens. Main conclusions Our data suggest that it is unlikely that species with very low phylogenetic relatedness to natives will become successful invaders with very high distribution in the area studied. To the contrary, under future climate warming scenarios, present‐day urban aliens of high occupancy frequency are likely to become successful invaders even outside urban areas. 相似文献
998.
999.
Bruno Lefebvre Sandrine Belaich Justine Longue Brigitte Vandewalle Jose Oberholzer François Pattou Julie Kerr-conte 《Biochemical and biophysical research communications》2010,391(1):305-309
Neurogenin 3 is necessary for endocrine cell development in the embryonic pancreas and has been shown to induce transdifferentiation duct cells from adult pancreas toward a neuro-endocrine phenotype. Here we discovered that the demethylating agent 5′-Azadeoxycytidine (AZA) induced Ngn3 expression and endocrine differentiation from the PANC-1 human ductal cell line. The expression of markers specific to mature islet cells, i.e., glucagon and somatostatin, was also observed. In addition, we demonstrated that growth factors (betacellulin and soluble factors released during pancreas embryogenesis) increased the level of maturation. Our studies revealed that the PANC-1 model system may provide a basis for elucidating the ductal/endocrine differentiation. 相似文献
1000.