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991.
Humans can register another person’s fear not only with their eyes and ears, but also with their nose. Previous research has demonstrated that exposure to body odors from fearful individuals elicited implicit fear in others. The odor of fearful individuals appears to have a distinctive signature that can be produced relatively rapidly, driven by a physiological mechanism that has remained unexplored in earlier research. The apocrine sweat glands in the armpit that are responsible for chemosignal production contain receptors for adrenalin. We therefore expected that the release of adrenalin through activation of the rapid stress response system (i.e., the sympathetic-adrenal medullary system) is what drives the release of fear sweat, as opposed to activation of the slower stress response system (i.e., hypothalamus-pituitary-adrenal axis). To test this assumption, sweat was sampled while eight participants prepared for a speech. Participants had higher heart rates and produced more armpit sweat in the fast stress condition, compared to baseline and the slow stress condition. Importantly, exposure to sweat from participants in the fast stress condition induced in receivers (N = 31) a simulacrum of the state of the sender, evidenced by the emergence of a fearful facial expression (facial electromyography) and vigilant behavior (i.e., faster classification of emotional facial expressions). 相似文献
992.
Monique Cachon Claude Greuet Jacky Cosson Philippe Huitorel 《Biology of the cell / under the auspices of the European Cell Biology Organization》1992,76(1):33-42
Summary— Dinoflagellates possess two flagella. One of them, the longitudinal flagellum, retracts from time to time in some species, such as Ceratium and Peridinium. Additional structures which run along the axoneme seem to be responsible for this particular behaviour. The retraction which is rapid (less than 60 ms) may be subdivided into several steps: i) the undulating movement stops; ii) the flagellum appears then as a jagged line during 20 ms; iii) finally a rapid retraction (20 ms) takes place, the flagellum being folded 20 times inside the cylindrical flagellar pocket. The measurements on video-records suggest that the R-fibre shortens to 30% of its original length. The contraction and relaxation mechanism of nanofilaments is proposed to be through coiling and uncoiling dependent on Ca2+ concentration. 相似文献
993.
Renee Toury Nicole Stelly Elizabeth Boisonneau Monique Convert Yvonne Dupuis 《Biology of the cell / under the auspices of the European Cell Biology Organization》1990,69(3):179-189
Summary— The effects of vitamin D on the intramuscular distribution of total and bound calcium, phosphate and on available cytosolic calcium, were investigated in skeletal muscle. Total calcium and phosphorus were measured on ashed subcellular fractions of muscles from vitamin D-repleted and vitamin D-deprived rats. The variations in available calcium were followed by determining the activities of calcium-sensitive enzymes in isolated cytosol. Bound-calcium was revealed ultra-microscopically by pyroantimonate. In vitamin D-repleted muscles, the pyroantimonate method revealed specific areas of intense bound-calcium deposition: the myofibrils, where they formed pronounced lines parallel to the Z-bands. In vitamin D-deficient muscles, the calcium-pyroantimonate deposits appeared clearly reduced. This loss was accompanied by a marked reduction in total calcium and phosphorus in all the subcellular fractions, as compared to vitamin D-repleted muscles. Unexpectedly, the activity of the Ca2+-activated isocitrate-dehydrogenase was increased in the cytosol, while that of the Ca2+-inhibited pyruvate-kinase decreased. Prolonged vitamin D-administration to vitamin D-repleted rats led to an intensification of calcium-pyroantimonate deposits and a general increase in total calcium and phosphorus, but no change in the cytosolic Ca2+-sensitive enzyme activities. Cessation of vitamin D-administration to vitamin D-repleted rats produced a regression of calcium-pyroantimonate deposits, a general decrease of total calcium and phosphate levels, and stimulation of the Ca2+-activated isocitrate-dehydrogenase accompanied by lowering of the Ca2+-inhibited pyruvate-kinase. The results clearly indicate a correlation between vitamin D-repletion and the total and bound calcium content of skeletal muscle. In addition, they demonstrate an apparent contradiction between the decrease of total and bound calcium, and the activities of cytosolic Ca2+ sensitive enzymes during vitamin D-deprivation, which can only be explained by an increase in available calcium. It is suggested that vitamin D stimulates intramuscular mechanisms tending to lower available calcium by inactivating the cation via the formation of calcium chelates. 相似文献
994.
995.
TOL plasmid pWW0 from Pseudomonas putida mt-2 encodes catabolic enzymes required for the oxidation of toluene and xylenes. The structural genes for these catabolic enzymes are clustered into two operons, the xylCMABN operon, which encodes a set of enzymes required for the transformation of toluene/xylenes to benzoate/toluates, and the xylXYZLTEGFJQKIH operon, which encodes a set of enzymes required for the transformation of benzoate/toluates to Krebs cycle intermediates. The latter operon can be divided physically and functionally into two parts, the xylXYZL cluster, which is involved in the transformation of benzoate/toluates to (methyl)catechols, and the xylTEGFJQKIH cluster, which is involved in the transformation of (methyl)catechols to Krebs cycle intermediates. Genes isofunctional to xylXYZL are present in Acinetobacter calcoaceticus, and constitute a benzoate-degradative pathway, while xylTEGFJQKIH homologous encoding enzymes of a methylphenol-degradative pathway and a naphthalene-degradative pathway are present on plasmid pVI150 from P. putida CF600, and on plasmid NAH7 from P. putida PpG7, respectively. Comparison of the nucleotide sequences of the xylXYZLTEGFJQKIH genes with other isofunctional genes suggested that the xylTEGFJQKIH genes on the TOL plasmid diverged from these homologues 20 to 50 million years ago, while the xylXYZL genes diverged from the A. calcoaceticus homologues 100 to 200 million years ago. In codons where amino acids are not conserved, the substitution rate in the third base was higher than that in synonymous codons. This result was interpreted as indicating that both single and multiple nucleotide substitutions contributed to the amino acid-substituting mutations, and hence to enzyme evolution. This observation seems to be general because mammalian globin genes exhibit the same tendency. 相似文献
996.
Claire Racaud-Sultan Grard Mauco Christine Guinebault Monique Plantavid Bernard Payrastre Monique Breton Hugues Chap 《FEBS letters》1993,330(3):347-351
When platelets are stimulated by thrombin they immediately undergo inositol lipid hydrolysis via phospholipase C activation. However, subsequently an increased production of phosphatidylinositol 4,5-bisphosphate is observed. Phospholipases C were inhibited by lowering the cytoplasmic free calcium concentration by preincubation with Quin-2-tetra(acetoxymethyl) ester. Aggregation and secretion were also totally suppressed. Under these conditions we observed an increased labeling of phosphatidylinositol 4,5-bisphosphate, indicating a stimulation of inositol lipid kinases, independent of lipid hydrolysis by phospholipase C. Conversely the production of phosphatidylinositol 3,4-bisphosphate was totally abolished. These results suggest a different regulation of the kinases/phosphatases responsible for the production of phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4-bisphosphate. 相似文献
997.
Elizabeth C. van Geerestein-Ujah Monique Slijper Rolf Boelens Robert Kaptein 《Journal of biomolecular NMR》1995,6(1):67-78
Summary A novel procedure is presented for the automatic identification of secondary structures in proteins from their corresponding NOE data. The method uses a branch of mathematics known as graph theory to identify prescribed NOE connectivity patterns characteristic of the regular secondary structures. Resonance assignment is achieved by connecting these patterns of secondary structure together, thereby matching the connected spin systems to specific segments of the protein sequence. The method known as SERENDIPITY refers to a set of routines developed in a modular fashion, where each program has one or several well-defined tasks. NOE templates for several secondary structure motifs have been developed and the method has been successfully applied to data obtained from NOESY-type spectra. The present report describes the application of the SERENDIPITY protocol to a 3D NOESY-HMQC spectrum of the 15N-labelled lac repressor headpiece protein. The application demonstrates that, under favourable conditions, fully automated identification of secondary structures and semi-automated assignment are feasible.Abbreviations 2D, 3D
two-, three-dimensional
- NOESY
nuclear Overhauser enhancement spectroscopy
- HMQC
heteronuclear multiple quantum coherence
- SSE
secondary structure element
- SERENDIPITY
SEcondary structuRE ideNtification in multiDImensional ProteIn specTra analYsis
Supplementary Material available from the authors: Two tables containing the total number of mappings resulting from the graph search procedure for simulated and experimental NOE data. 相似文献
998.
In Chrysanthemum leaf explants cultivated in vitro the capacity to covalently link polyamines to protein substances exists. This plant enzyme activity shows some similarities with mammalian transglutaminases. In foliar explants cultured on a medium promoting bud or root formation increasing levels of transglutaminase-like activity occurred during the first days of culture when cell multiplication was rapid then the levels declined as the rate of cell division decreased and differentiation occurred. Undifferentiated callus exhibited low transglutaminase-like activity. Transglutaminase-like activity also increased in rapidly proliferating and growing organs (roots and buds initiated from the foliar explants) and decreased during maturity. The relationship among transglutaminases-like activity, cell division, bud and root formation is discussed. 相似文献
999.
Fred Van Leuven Sophie Torrekens Dieder Moechars Carl Hilliker Monique Buellens Mathieu Bollen Jan Delabie 《Genomics》1998,54(3):511
A novel protein, named NNX3, was molecularly characterized by cloning its cDNA, and its gene was mapped to chromosome 19q12. The equivalent mouse cDNA and gene were also cloned to allow us to analyze expression in murine in addition to human cells and tissues. Human and mouse NNX3 genes are composed of nine exons coding for proteins that are unrelated to any known protein. Signal peptides and hydrophobic domains are absent, corroborating their localization in the cytoplasm in transfected Cos cells. In Western blotting and immunoprecipitation, human NNX3 appeared as a doublet ofMr64K–66K, while mouse NNX3 was a 70-kDa protein, both apparently much larger than the predicted 50 kDa, due in part to a stretch of 16–18 acidic residues hinging two nearly equally sized domains. In addition, phosphorylation of serine residues was demonstrated. Putative nuclear targeting signals were predicted, but NNX3 protein and two truncated versions remained localized in the cytoplasm of transfected Cos cells. NNX3 was expressed in embryonic and adult mouse tissues, particularly in brain, muscle, and lung. The expression of human NNX3 was most notable in human skeletal muscle and in ganglion cells and was also evident in human tumors and derived cell lines. This was confirmed by entries appearing in the GenBank EST database during the later phase of this study, representing partial NNX3 cDNA isolated from diverse neoplastic and developing tissues. Surprisingly, NNX3 was immunochemically detected in Reed–Sternberg cells of Hodgkin disease, in parallel with restin, a cytoplasmic protein we previously characterized (J. Delabieet al.,1993,Leuk. Lymphoma 12,21–26). The cloning and comprehensive molecular analysis of NNX3 as presented will form the basis for elucidating its function and, conversely, will constitute a marker for Reed–Sternberg cells in Hodgkin disease. 相似文献
1000.
Christine Sacerdot Joel Caillet Monique Graffe Flore Eyermann Bernard Ehresmann Chantal Ehresmann Mathias Springer & Pascale Romby 《Molecular microbiology》1998,29(4):1077-1090
The expression of the gene encoding Escherichia coli threonyl-tRNA synthetase (ThrRS) is negatively autoregulated at the translational level. ThrRS binds to its own mRNA leader, which consists of four structural and functional domains: the Shine–Dalgarno (SD) sequence and the initiation codon region (domain 1); two upstream hairpins (domains 2 and 4) connected by a single-stranded region (domain 3). Using a combination of in vivo and in vitro approaches, we show here that the ribosome binds to thrS mRNA at two non-contiguous sites: region −12 to +16 comprising the SD sequence and the AUG codon and, unexpectedly, an upstream single-stranded sequence in domain 3. These two regions are brought into close proximity by a 38-nucleotide-long hairpin structure (domain 2). This domain, although adjacent to the 5' edge of the SD sequence, does not inhibit ribosome binding as long as the single-stranded region of domain 3 is present. A stretch of unpaired nucleotides in domain 3, but not a specific sequence, is required for efficient translation. As the repressor and the ribosome bind to interspersed domains, the competition between ThrRS and ribosome for thrS mRNA binding can be explained by steric hindrance. 相似文献