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91.
92.
Professor Bertrand Kerebel Marie-Thérèse Le Cabellec Guy Daculsi Lise-Marie Kerebel 《Cell and tissue research》1978,187(1):135-146
Summary TEM, SEM and X-ray diffraction analysis demonstrate the heterogeneity of the dentinal tissue of Anarhichas lupus, a vascular osteodentine. The disordered aspect of collagen fibres, incompletely mineralized (the periodical striation being still visible), explains the scattered distribution of crystallites since they are responsible for their arrangement. The low degree of mineralization revealed by the visible collagen striation is confirmed by X-ray diffraction analysis (the crystallinity of vascular osteodentine being much lower than that of the peripheral dental tissue) as well as by high resolution TEM, since no lattice planes could be observed. Osteodentine, supporting bone and proper bone have in common a mineral phase, more or less organized, different from the apatite system.The authors thank Mireille Cottrel-Gengoux for her technical assistance 相似文献
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Summary Fox and Woese (1975a) have shown that a model of 5S RNA secondary structure similar to the one originally derived forChlorella 5S RNA can be generalized with relatively minor variations to all sequenced 5S RNA molecules, i.e. that corresponding base paired regions can be formed at approximately the same positions. We present experimental data in favour of this hypothesis and show that the points at which ribonucleases T1, T2 and pancreatic ribonuclease cleave six different 5S RNA molecules under mild conditions (high ionic strength, low temperature, low RNAase concentration) nearly always fall in the proposed single-stranded regions. We conclude that this model is a good approximation to the conformation of 5S RNA in solution. 相似文献
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In 234 copulations, male and female behavioural patterns were collected, especially the vocal pattern for the female. Moreover
quantitative structural analysis was performed on 38 of these female copulatory vocalizations. A multifactorial analysis,
ANAFAC, was performed to seek relations between (1) utterance of female copulatory call and male and female copulatory behaviour
and (2) these patterns and the great variability of female calls. Utterance of female copulatory vocalizations is essentially
due to the female’s own copulatory behaviour in periods of intense sexual activity. Long female calls are related to male
ejaculation, and those “rich” in harmonics are related to visual and tactile communicatory signals exchanged by the male and
the female during a mount. This analysis strongly confirms the tied bond between quality of a call and internal state of the
emitter. Long calls, rich in harmonics, may serve as signals maintaining or strengthening the possibly temporary preferential
relation between male and sexually receptive female. 相似文献
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Michel Y. Popoff Colette Coynault Martine Kiredjian Muguette Lemelin 《Current microbiology》1981,5(2):109-114
Relatedness among 55 motileAeromonas strains was assessed by determining the extent of reassociation in heterologous DNA preparations. S1 nuclease and diethylaminoethyl-cellulose filters were used to separate reassociated nucleotide sequences from nonreassociated sequences and to determine the thermal stability of related nucleotide sequences. The motile aeromonads would presently consist of three species:A. hydrophila (type strain ATCC 7966),A. caviae (type strain ATCC 15468), andA. sobria (type strain CIP 7433). These three species are clearly separated on the basis of both biochemical characteristics and similarities in DNA. Each of these three species contains more than one hybridization group: three groups inA. hydrophila; two groups inA. caviae; and at least two groups inA. sobria. DNA hybridization groups are biochemically similar within each species. When additional data is available, these separate DNA hybridization groups may merit designation. Any decision to delineate species in terms of DNA hybridization groups must await a phenotypic basis for their separation. 相似文献
100.
Summary Preincubation at 42o, before infection at permissive temperature by phage , of an Escherichia coli dnaB mutant, provokes a significant increase in survival and mutagenesis of ultraviolet irradiated phage as well as mutagenesis of untreated phage. Similarly to UV irradiation and many chemical mutagens, the inhibition of DNA synthesis by temperature shift of this dnaB mutant induces SOS repair. This work shows that replication blockage in bacterial DNA is not only mutagenic for bacterial DNA itself (Witkin, 1975) but also for normally replicating DNA, probably due to induction of diffusible products. 相似文献