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151.
Milena Z. Živković Stošić Niko S. Radulović Marija S. Genčić Vladimir N. Ranđelović 《化学与生物多样性》2021,18(7):e2100285
Herein n-, iso- and anteiso-series of very-long-chained (VLC) alkanes (C21–C35), fatty acid benzyl esters (FABEs; C20–C32), and 2-alkanones (C23–C35) were identified in the wax of Primula veris L. and P. acaulis (L.) L. (Primulaceae). For the very first time in a sample of natural origin, the presence of iso- and anteiso-VLC FABEs and 2-alkanones was unequivocally confirmed by synthetic work, derivatization, and NMR. It should be noted that the studied species produced unusually high amounts of branched wax constituents (e. g., >50 % of 2-alkanones were branched isomers). The domination of iso-isomers, probably biosynthesized from leucine-derived starters, is a unique feature in the Plant Kingdom. The plant organ distribution of these VLC compounds in P. acaulis samples (different habitats and phenological phases) pointed to their possible ecological value. This was supported by a eutectic behavior of binary blends of FABEs and alkanes, as well as by high UV-C absorption by FABEs. 相似文献
152.
Intraperitoneal administration of the mycotoxin penitrem A 30 min before a training session in passive avoidance task, impaired
performance of rats subjected to a test-session 24 h after. This effect was not antagonised by pretraining administration
of physostigmine or bicuculline. Administration of penitrem A 20 min before a training session or 30 min before a test-session
did not impair performance. In the Morris water maze, doses of penitrem A that induces slight to moderate tremors, but not
a lower dose, disrupted place learning. These results suggest that penitrem A disrupts the processes that take place at the
time of acquisition, but not those just after acquisition, and does not alter the restitution of information. This effect
would not be related to a decrease of cholinergic neurotransmission nor to a stimulation of GABA A receptors. Nevertheless,
it could not be totally excluded that the performance impairments induced by penitrem A would be secondary to a motor disruption.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
153.
Moussaïd M Guillot EG Moreau M Fehrenbach J Chabiron O Lemercier S Pettré J Appert-Rolland C Degond P Theraulaz G 《PLoS computational biology》2012,8(3):e1002442
In human crowds as well as in many animal societies, local interactions among individuals often give rise to self-organized collective organizations that offer functional benefits to the group. For instance, flows of pedestrians moving in opposite directions spontaneously segregate into lanes of uniform walking directions. This phenomenon is often referred to as a smart collective pattern, as it increases the traffic efficiency with no need of external control. However, the functional benefits of this emergent organization have never been experimentally measured, and the underlying behavioral mechanisms are poorly understood. In this work, we have studied this phenomenon under controlled laboratory conditions. We found that the traffic segregation exhibits structural instabilities characterized by the alternation of organized and disorganized states, where the lifetime of well-organized clusters of pedestrians follow a stretched exponential relaxation process. Further analysis show that the inter-pedestrian variability of comfortable walking speeds is a key variable at the origin of the observed traffic perturbations. We show that the collective benefit of the emerging pattern is maximized when all pedestrians walk at the average speed of the group. In practice, however, local interactions between slow- and fast-walking pedestrians trigger global breakdowns of organization, which reduce the collective and the individual payoff provided by the traffic segregation. This work is a step ahead toward the understanding of traffic self-organization in crowds, which turns out to be modulated by complex behavioral mechanisms that do not always maximize the group's benefits. The quantitative understanding of crowd behaviors opens the way for designing bottom-up management strategies bound to promote the emergence of efficient collective behaviors in crowds. 相似文献
154.
Human and animal cremated osteological remains from twelve graves of Roman Period from archaeological site Sepkovcica near Velika Gorica (Turopolje region, NW Croatia) were analysed. Beside the content of urns and grave pits, fillings of grave vessels like bowls, pots and amphoras from twentytwo grave samples were included in this study. The preservation of osteological and dental remains of human and animal origin was very poor, majority of fragments hardly reach lengths of 10 mm. Weight of each specimen barely exceeds 100 g per person. Apart from traditional macroscopic methods of analysing cremated remains, microscopic method for determination of age at death was also tested. Fragments of femoral bone diaphysis of eighteen persons whose remains had been found on the site were analysed. Person's age at death was presented in the range of five or ten years, and the long bone fragments of a child (infants) were detected. Taxonomic position for each analysed specimen was determined by microscopic analysis of animal cremated bones. Analysis results confirm validity of microscopic method in determination of age at death for human remains and taxonomic qualification of cremated animal remains from archaeological sites. 相似文献
155.
Neisseria meningitidis infection of human endothelial cells interferes with leukocyte transmigration by preventing the formation of endothelial docking structures 下载免费PDF全文
Doulet N Donnadieu E Laran-Chich MP Niedergang F Nassif X Couraud PO Bourdoulous S 《The Journal of cell biology》2006,173(4):627-637
Neisseria meningitidis elicits the formation of membrane protrusions on vascular endothelial cells, enabling its internalization and transcytosis. We provide evidence that this process interferes with the transendothelial migration of leukocytes. Bacteria adhering to endothelial cells actively recruit ezrin, moesin, and ezrin binding adhesion molecules. These molecules no longer accumulate at sites of leukocyte-endothelial contact, preventing the formation of the endothelial docking structures required for proper leukocyte diapedesis. Overexpression of exogenous ezrin or moesin is sufficient to rescue the formation of docking structures on and leukocyte migration through infected endothelial monolayers. Inversely, expression of the dominant-negative NH(2)-terminal domain of ezrin markedly inhibits the formation of docking structures and leukocyte diapedesis through noninfected monolayers. Ezrin and moesin thus appear as pivotal endothelial proteins required for leukocyte diapedesis that are titrated away by N. meningitidis. These results highlight a novel strategy developed by a bacterial pathogen to hamper the host inflammatory response by interfering with leukocyte-endothelial cell interaction. 相似文献
156.
157.
Jespersen T Gavillet B van Bemmelen MX Cordonier S Thomas MA Staub O Abriel H 《Biochemical and biophysical research communications》2006,348(4):1455-1462
In order to identify proteins interacting with the cardiac voltage-gated sodium channel Na(v)1.5, we used the last 66 amino acids of the C-terminus of the channel as bait to screen a human cardiac cDNA library. We identified the protein tyrosine phosphatase PTPH1 as an interacting protein. Pull-down experiments confirmed the interaction, and indicated that it depends on the PDZ-domain binding motif of Na(v)1.5. Co-expression experiments in HEK293 cells showed that PTPH1 shifts the Na(v)1.5 availability relationship toward hyperpolarized potentials, whereas an inactive PTPH1 or the tyrosine kinase Fyn does the opposite. The results of this study suggest that tyrosine phosphorylation destabilizes the inactivated state of Na(v)1.5. 相似文献
158.
Candida albicans is the most prevalent yeast pathogen in humans, and recently it has become increasingly resistant to the current antifungal agents. In this study we investigated C. albicans dihydroorotate dehydrogenase (DHODH, EC 1.3.99.11), which catalyzes the fourth step of de novo pyrimidine synthesis, as a new target for controlling infection. We propose that the enzyme is a member of the DHODH family 2, which comprises mitochondrially bound enzymes, with quinone as the direct electron acceptor and oxygen as the final electron acceptor. Full-length DHODH and N-terminally truncated DHODH, which lacks the targeting sequence and the transmembrane domain, were subcloned from C. albicans, recombinantly expressed in Escherichia coli, purified, and characterized for their kinetics and substrate specificity. An inhibitor screening with 28 selected compounds was performed. Only the dianisidine derivative, redoxal, and the biphenyl quinoline-carboxylic acid derivative, brequinar sodium, which are known to be potent inhibitors of mammalian DHODH, markedly reduced C. albicans DHODH activity. This study provides a background for the development of antipyrimidines with high efficacy for decreasing in situ pyrimidine nucleotide pools in C. albicans. 相似文献
159.
Py B Bouchet J Jacquot G Sol-Foulon N Basmaciogullari S Schwartz O Biard-Piechaczyk M Benichou S 《Apoptosis : an international journal on programmed cell death》2007,12(10):1879-1892
In addition to its positive signaling function in the antigen presentation process, CD4 acts as the primary receptor for HIV-1.
Contact between CD4 and the viral envelope leads to virus entry, but can also trigger apoptosis of uninfected CD4+ T-cells through a mechanism that is poorly understood. We show that Siva-1, a death domain-containing proapoptotic protein,
associates with the cytoplasmic domain of CD4. This interaction is mediated by the cysteine-rich region found in the C-terminal
part of the Siva-1 protein. Expression of Siva-1 specifically increases the susceptibility of both T-cell lines and unstimulated
human primary CD4+ T-lymphocytes to CD4-mediated apoptosis triggered by the HIV-1 envelope, and results in activation of a caspase-dependent
mitochondrial pathway. The same susceptibility is observed in T-cells expressing a truncated form of CD4 that is able to recruit
Siva-1 but fails to associate with p56Lck, indicating that Siva-1 participates in a pathway independent of the p56Lck kinase activity. Altogether, these results suggest that Siva-1 might participate in the CD4-initiated signaling apoptotic
pathway induced by the HIV-1 envelope in T-lymphoid cells.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
160.
Jean-Louis Spadoni Pierre Rucart Sigrid Le Clerc Dani?lle van Manen Cédric Coulonges Damien Ulveling Vincent Laville Taoufik Labib Lieng Taing Olivier Delaneau Matthieu Montes Hanneke Schuitemaker Josselin Noirel Jean-Fran?ois Zagury 《PloS one》2015,10(9)