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81.
Dr. Laura Curatolo Christine Chaponnier Maria Benedetta Donati Luciano Morasca Giulio Gabbiani 《Cell and tissue research》1982,223(3):665-673
Summary It is known that human and animal fibroblasts are able to induce the retraction of a fibrin clot. In the present study the correlation between (i) fibrinclot retractile (FCR) activity, (ii) the number of actin stress-lines in mouse fibroblasts during growth in culture, and (iii) the sensitivity of actin stress-lines to a powerful actin-depolymerizing factor (ADF), present in plasma and serum of humans and laboratory animals was investigated. Fibroblasts at early passages (2–4) were tested for these parameters at various intervals after seeding (24, 96, and 168 h). The number of actin stress-lines was progressively higher, while the sensitivity to ADF action was progressively lower in cells cultured from 24 to 168 h; the FCR capacity was significantly decreased at 168 h. These data suggest that cells containing weakly polymerized and/or stabilized actin are more active than those containing highly polymerized and/or stabilized actin in triggering fibroblast contraction. 相似文献
82.
Age-dependent population diffusion with external constraint 总被引:3,自引:0,他引:3
We present a simple model for age dependent population diffusion when the dynamics is submitted to external constraints. Existence, uniqueness and dependence on the parameters of the solution are discussed.This work has been done within the framework of the cultural agreement between the Universities of Bordeaux and Rome 相似文献
83.
84.
85.
Replication of bacteriophage lambda DNA. Examination of variants containing double origins and observation of a bias in directionality 总被引:1,自引:0,他引:1
Maria Schnös Katherine J. Denniston Frederick R. Blattner Ross B. Inman 《Journal of molecular biology》1982,159(3):441-455
Bacteriophage λ variants have been constructed that possess two λ ori sites. Replicative intermediates resulting from infection with these phages have been investigated. We find that initiation of replication from the ori site on an EcoRI fragment (containing all the DNA sequences from within the red gene to the middle of gene O) cloned in the inverted orientation is predominantly bidirectional but occurs at a decreased frequency. Double initiations were observed at low frequency. However, a second cloned ori fragment (carrying two large deletions and a small insertion) cloned in the normal orientation demonstrated insignificant levels of replication from the cloned site unless the normal ori had already initiated.A bias in directionality of λ replication has been observed. Molecules that replicate unidirectionally propagate to the right more often than to the left. If the cloned ori-containing EcoRI fragment is inserted with reversed polarity, then the bias is towards the left. Bidirectional λ replicative intermediates also appear to show a similar bias but this is superimposed on a large, apparently random, effect that results in asymmetric growing-point propagation. 相似文献
86.
Mario De Rosa Agata Gambacorta Barbara Nicolaus Salvatore Sodano J.D. BuLock 《Phytochemistry》1980,19(5):833-836
Individual di(biphytanyl) diglycerol tetraether lipids from thermoacidophile archaebacteria of the Caldariella series, with differently cyclized biphytanyl components, are separated and shown to have structures 8–12, with the glycerol and biphytanyl components demonstrably both antiparallel and with partial assignments of stereochemistry. Tetraethers with alternative arrangements of the components are absent. The structures allow previous observations on these and related lipids to be rationalized both biosynthetically and phyletically. 相似文献
87.
Howard R. Morris Maria Panico Michael Barber Robert S. Bordoli Robert D. Sedgwick Andrew Tyler 《Biochemical and biophysical research communications》1981,101(2):623-631
We have studied a selection of peptides using a new mass spectrometric ionisation technique - fast atom bombardment (FAB). We define the fragmentation pathways observed and comment on the utility in sequence analysis. A simple acetylation experiment is shown to aid rapid sequence assignment. 相似文献
88.
89.
Maria L. Bade Alfred Stinson 《Biochemical and biophysical research communications》1978,84(2):381-388
During the molt, chitin in the old cuticle of is digested by chitinase taken up from molting fluid, but the chitin in intact (= premolt) cuticle is not accessible to chitinase. As a prerequisite of digestion, old cuticle chitin is rendered competent to serve as chitinase substrate in a reaction attributable to trypsin-like proteolytic activity of molting fluid. 相似文献
90.
Maria A. A. Schipper 《Antonie van Leeuwenhoek》1976,42(1-2):141-144
Attempts to determine the mating reaction type of heterothallic strains of Mucor pusillus in interspecific contrasts with Mucor strains of known mating reaction type were unsuccessful. Contrasts with Absidia corymbifera strains resulted in the production of azygospores in Mucor pusillus. 相似文献