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Peritoneal macrophages were isolated from wild type (WT) mice and from mice invalidated for the P2X7 receptor (KO) which had been pretreated with thioglycolate. In cells from WT mice, 1 mM ATP increased the intracellular concentration of calcium ([Ca2+]i), the uptake of ethidium bromide, the production of reactive oxygen species (ROS), the secretion of IL-1β, the release of oleic acid and of lactate dehydrogenase; it decreased the intracellular concentration of potassium ([K+]i). In KO mice, ATP transiently increased the [Ca2+]i confirming that the P2X7 receptor is a major receptor of peritoneal macrophages. WKYMVm, an agonist of receptors for formylated peptides (FPR) also increased the [Ca2+]i in murine macrophages. The slight increase of the [Ca2+]i was strongly potentiated by ivermectin confirming the expression of functional P2X4 receptors by murine peritoneal macrophages. CRAMP, the unique antimicrobial peptide derived from cathelin in mouse inhibited all the responses coupled to P2X7 receptors in macrophages from WT mice. Agonists for FPR had no effect on the increase of the [Ca2+]i in response to ATP. CRAMP had no effect on the increase of the [Ca2+]i evoked by a combination of ATP and ivermectin in macrophages from P2X7-KO mice.In summary CRAMP inhibits the responses secondary to the activation of the murine P2X7 receptors expressed by peritoneal macrophages. This inhibition is not mediated by FPR receptors and is specific since CRAMP has no effect on the response coupled to P2X4 receptors. It can thus be concluded that the interaction between P2X7 receptors and cathelin-derived antimicrobial peptides is species-specific, in some cases (man) positive in others (mouse) negative. 相似文献
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Actin ADP‐ribosylation at Threonine148 by Photorhabdus luminescens toxin TccC3 induces aggregation of intracellular F‐actin 下载免费PDF全文
Alexander E. Lang Zheng Qu Carsten Schwan Unai Silvan Andreas Unger Cora‐Ann Schoenenberger Klaus Aktories Hans Georg Mannherz 《Cellular microbiology》2017,19(1)
Intoxication of eukaryotic cells by Photorhabdus luminescens toxin TccC3 induces cell rounding and detachment from the substratum within a few hours and compromises a number of cell functions like phagocytosis. Here, we used morphological and biochemical procedures to analyse the mechanism of TccC3 intoxication. Life imaging of TccC3‐intoxicated HeLa cells transfected with AcGFP‐actin shows condensation of F‐actin into large aggregates. Life cell total internal reflection fluorescence (TIRF) microscopy of identically treated HeLa cells confirmed the formation of actin aggregates but also disassembly of F‐actin stress fibres. Recombinant TccC3 toxin ADP‐ribosylates purified skeletal and non‐muscle actin at threonine148 leading to a strong propensity to polymerize and F‐actin bundle formation as shown by TIRF and electron microscopy. Native gel electrophoresis shows strongly reduced binding of Thr148‐ADP‐ribosylated actin to the severing proteins gelsolin and its fragments G1 and G1–3, and to ADF/cofilin. Complexation of actin with these proteins inhibits its ADP‐ribosylation. TIRF microscopy demonstrates rapid polymerization of Thr148‐ADP‐ribosylated actin to curled F‐actin bundles even in the presence of thymosin β4, gelsolin or G1–3. Thr148‐ADP‐ribosylated F‐actin cannot be depolymerized by gelsolin or G1–3 as verified by TIRF, co‐sedimentation and electron microscopy and shows reduced treadmilling as indicated by a lack of stimulation of its ATPase activity after addition of cofilin‐1. 相似文献
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Summary The conversion of whey to single-cell protein by yeasts was investigated. The most suitable organism tested wasKluyveromyces
marxianus NCYC 1424. The efficiency of whey conversion to biomass was directly related to higher oxygen availability in the medium. 相似文献
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Per M. Stromberg Unai Pascual Mauricio R. Bellon 《Human ecology: an interdisciplinary journal》2010,38(4):539-553
This paper analyzes how local seed system institutions support seed diversity, itself a requirement for agrobiodiversity maintained
on-farm. The paper focuses on maize seed diversity in the central Peruvian Amazon. Using household and community level data
from three different cultural groups from the central Peruvian Amazon, empirical results show the importance of collective
action and the mediating role of ethnicity in the functioning of informal seed systems that in turn affect farmers’ choices
regarding conservation of seed diversity. This implies that policies are needed to protect the relatively open seed exchanges
of such local practices as a way to sustain on-farm agrobiodiversity. 相似文献
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