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11.
Marie Armani-Tourret Zhicheng Zhou Romain Gasser Isabelle Staropoli Vincent Cantaloube-Ferrieu Yann Benureau Javier Garcia-Perez Mayte Prez-Olmeda Valrie Lorin Bndicte Puissant-Lubrano Lambert Assoumou Constance Delaugerre Jean-Daniel Lelivre Yves Lvy Hugo Mouquet Guillaume Martin-Blondel Jose Alcami Fernando Arenzana-Seisdedos Jacques Izopet Philippe Colin Bernard Lagane 《PLoS pathogens》2021,17(4)
HIV-1 infects CD4 T lymphocytes (CD4TL) through binding the chemokine receptors CCR5 or CXCR4. CXCR4-using viruses are considered more pathogenic, linked to accelerated depletion of CD4TL and progression to AIDS. However, counterexamples to this paradigm are common, suggesting heterogeneity in the virulence of CXCR4-using viruses. Here, we investigated the role of the CXCR4 chemokine CXCL12 as a driving force behind virus virulence. In vitro, CXCL12 prevents HIV-1 from binding CXCR4 and entering CD4TL, but its role in HIV-1 transmission and propagation remains speculative. Through analysis of thirty envelope glycoproteins (Envs) from patients at different stages of infection, mostly treatment-naïve, we first interrogated whether sensitivity of viruses to inhibition by CXCL12 varies over time in infection. Results show that Envs resistant (RES) to CXCL12 are frequent in patients experiencing low CD4TL levels, most often late in infection, only rarely at the time of primary infection. Sensitivity assays to soluble CD4 or broadly neutralizing antibodies further showed that RES Envs adopt a more closed conformation with distinct antigenicity, compared to CXCL12-sensitive (SENS) Envs. At the level of the host cell, our results suggest that resistance is not due to improved fusion or binding to CD4, but owes to viruses using particular CXCR4 molecules weakly accessible to CXCL12. We finally asked whether the low CD4TL levels in patients are related to increased pathogenicity of RES viruses. Resistance actually provides viruses with an enhanced capacity to enter naive CD4TL when surrounded by CXCL12, which mirrors their situation in lymphoid organs, and to deplete bystander activated effector memory cells. Therefore, RES viruses seem more likely to deregulate CD4TL homeostasis. This work improves our understanding of the pathophysiology and the transmission of HIV-1 and suggests that RES viruses’ receptors could represent new therapeutic targets to help prevent CD4TL depletion in HIV+ patients on cART. 相似文献
12.
Structure and growth pattern of the bizarre hemispheric prominence on the rostrum of the fossil beaked whale Globicetus hiberus (Mammalia,Cetacea, Ziphiidae)
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Maïtena Dumont Vivian de Buffrénil Ismael Miján Olivier Lambert 《Journal of morphology》2016,277(10):1292-1308
The rostrum of most ziphiids (beaked whales) displays bizarre swollen regions, accompanied with extreme hypermineralisation and an alteration of the collagenous mesh of the bone. The functional significance of this specialization remains obscure. With the voluminous and dense hemispheric excrescence protruding from the premaxillae, the recently described fossil ziphiid Globicetus hiberus is the most spectacular case. This study describes the histological structure and interprets the growth pattern of this unique feature. Histologically, the prominence in Globicetus is made up of an atypical fibro‐lamellar complex displaying an irregular laminar organization and extreme compactness (osteosclerosis). Its development is suggested to have resulted from a protraction of periosteal accretion over the premaxillae, long after the end of somatic growth. Complex shifts in the geometry of this tissue are likely to have occurred during its accretion and no indication of Haversian remodeling could be found. X‐ray diffraction and Raman spectroscopy indicate that the bone matrix in the premaxillary prominence of Globicetus closely resembles that of the rostrum of the extant beaked whale Mesoplodon densirostris: apatite crystals are of common size and strongly oriented, but the collagenous meshwork within bone matrix seems to be extremely sparse. These morphological and structural data are discussed in the light of functional interpretations proposed for the highly unusual and diverse ziphiid rostrum. J. Morphol. 277:1292–1308, 2016. © 2016 Wiley Periodicals, Inc. 相似文献
13.
The cyanobacterium Anabaena cylindrica B629 was suspended in small glass beds and incubated in a gas-tight glass vessel outdoors under a gas atmosphere comprising carbon monoxide (0.2%), acetylene (5%), oxygen (6.5%), and nitrogen. The solution phase initially contained sodium bicarbonate (10mM) at pH 7. Under these conditions the organism continuously produced hydrogen gas for over three weeks. The temperature of the culture was maintained below 30°C and minimum night temperatures were recorded. The vessel was covered by a shadecloth, which reduced the natural illumination by approximately 70%. The system is an alternative to those requiring the strict absence of oxygen and little nitrogen, and requires virtually no attention during the incubation period. 相似文献
14.
15.
Patricia M. Lambert 《American anthropologist》2000,102(1):166-167
Prehistoric Warfare in the American Southwest. Steven A. LeBlanc. Salt Lake City: University of Utah Press, 1999 400 pp. 相似文献
16.
Characterization and dynamics of cytoplasmic F-actin in higher plant endosperm cells during interphase, mitosis, and cytokinesis 总被引:3,自引:0,他引:3
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We have identified an F-actin cytoskeletal network that remains throughout interphase, mitosis, and cytokinesis of higher plant endosperm cells. Fluorescent labeling was obtained using actin monoclonal antibodies and/or rhodamine-phalloidin. Video-enhanced microscopy and ultrastructural observations of immunogold-labeled preparations illustrated microfilament-microtubule co-distribution and interactions. Actin was also identified in cell crude extract with Western blotting. During interphase, microfilament and microtubule arrays formed two distinct networks that intermingled. At the onset of mitosis, when microtubules rearranged into the mitotic spindle, microfilaments were redistributed to the cell cortex, while few microfilaments remained in the spindle. During mitosis, the cortical actin network remained as an elastic cage around the mitotic apparatus and was stretched parallel to the spindle axis during poleward movement of chromosomes. This suggested the presence of dynamic cross-links that rearrange when they are submitted to slow and regular mitotic forces. At the poles, the regular network is maintained. After midanaphase, new, short microfilaments invaded the equator when interzonal vesicles were transported along the phragmoplast microtubules. Colchicine did not affect actin distribution, and cytochalasin B or D did not inhibit chromosome transport. Our data on endosperm cells suggested that plant cytoplasmic actin has an important role in the cell cortex integrity and in the structural dynamics of the poorly understood cytoplasm-mitotic spindle interface. F-actin may contribute to the regulatory mechanisms of microtubule-dependent or guided transport of vesicles during mitosis and cytokinesis in higher plant cells. 相似文献
17.
D J McCormick G E Griesmann Z X Huang E H Lambert V A Lennon 《Journal of immunology (Baltimore, Md. : 1950)》1987,139(8):2615-2619
This study reports the synthesis of a disulfide-looped peptide corresponding to residues 125-147 (Cys 128-Cys 142) of the nicotinic acetylcholine receptor (AChR) of human skeletal muscle, H alpha 125-147 (Lys-Ser-Tyr-Cys-Glu-Ile-Ile-Val-Thr-His-Phe-Pro-Phe-Asp-Glu-Gln- Asn-Cys-Ser-Nle-Lys Leu-Gly), and a nondisulfide-looped analogue, H alpha 125-147(S) (Lys-Ser-Tyr-Ser-Glu-Ile-Ile-Val-Thr-His-Phe-Pro-Phe-Asp-Glu- Gln-Asn-Cys-Ser-Nle-Lys-Leu-Gly), in which the amino acid Cys 128 was replaced with serine. Both peptides induced antigen-specific helper T cell responses, as evidenced in vitro by lymph node cell proliferation and in vivo by production of anti-AChR antibodies. Rats immunized with 100 micrograms of either synthetic peptide, without conjugation to a carrier, produced anti-peptide antibodies which bound to native AChR in immunoprecipitation assays and induced modulation of membrane-bound AChR from cultured human myotubes. Both peptides also induced electrophysiologic and biochemical signs of experimental autoimmune myasthenia gravis. Thus, region 125-147 of the AChR alpha-subunit is at least partly exposed extracellularly in human muscle and contains one or more autoantigenic sites capable of stimulating T cells and B cells. Disulfide-linkage between residues Cys 128 and Cys 142 is not essential for myasthenogenicity. 相似文献
18.
Enhancement of major histocompatibility class I protein synthesis by DNA damage in cultured human fibroblasts and keratinocytes. 总被引:3,自引:0,他引:3
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Exposure of primary human fibroblasts or simian virus 40-transformed human keratinocytes to several different classes of DNA damage, including UV light C (254 nm), resulted in a rapid increase in the expression of human major histocompatibility class I (MHC-I) proteins. MHC-I induction was also detected after exposure to low doses of the protein synthesis inhibitor cycloheximide, suggesting that MHC-I induction by DNA damage may be a component in a derepressible cellular SOS pathway. 相似文献
19.
Muscarinic-receptor-mediated changes in intracellular Ca2+ and inositol 1,4,5-trisphosphate mass in a human neuroblastoma cell line, SH-SY5Y. 总被引:7,自引:0,他引:7
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This study reports increased intracellular Ca2+ and inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] in response to muscarinic-cholinergic stimulation of human neuroblastoma (SH-SY5Y) cells. Carbachol stimulation leads to a rapid increase in intracellular Ca2+ and Ins(1,4,5)P3 mass, both reaching a peak at around 10 s and then declining to a new maintained phase significantly above basal. Dose-response analysis of peak and plateau phases of intracellular Ca2+ shows different agonist potencies for both phases, carbachol being more potent for the plateau phase. The plateau-phase intracellular Ca2+ was dependent on extracellular Ca2+, which is admitted to the cell through a non-voltage-sensitive Ni2(+)-blockable Ca2+ channel. Using a Mn2+ quench protocol, we have shown that Ca2+ entry occurs early during the discharge of the internal stores. The plateau phase (Ca2(+)-channel opening) is dependent on the continued presence of agonist, since addition of atropine closes the Ca2+ channel and intracellular Ca2+ declines rapidly back to basal. We also failed to detect a refilling transient when we added back Ca2+ after intracellular Ca2+ had reached a peak and then declined in Ca2(+)-free conditions. These data strongly suggest that muscarinic stimulation of SH-SY5Y cells leads to a rapid release of Ca2+ from an Ins(1,4,5)P3-sensitive internal store and a parallel early entry of Ca2+ across the plasma membrane. 相似文献
20.
Marie-Claude Pepin Serge Beaulieu Nicholas Barden 《Cellular and molecular neurobiology》1990,10(2):227-235
1. Differential regulation, by dexamethasone, of glucocorticoid receptor gene expression was studied in three different neuronal cultures derived from hypothalamus amygdala, and cerebral cortex. 2. Cellular glucocorticoid receptor (GR) mRNA concentration was measured by hybridization using a 32P-labeled RNA probe complementary to a 2.2-kb fragment of the glucocorticoid receptor mRNA. Changes in the amount of GR mRNA were evaluated in relation to the content of beta-actin mRNA. 3. In cells derived from either hypothalamus or cerebral cortex, we observed a complex pattern of GR mRNA concentrations which were characterized by cyclic variations of GR mRNA content during continuous treatment with dexamethasone for up to 72 hr. 4. In contrast to cells derived from the hypothalamus where a persistent 30-40% reduction in GR mRNA levels was seen for up to a least 72 hr, we observed, in cells derived from the cerebral cortex, a sustained increased (1.4-fold) of the GR mRNA at this same time interval. 相似文献