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31.
Innovation in wild chimpanzees (Pan troglodytes) 总被引:5,自引:0,他引:5
Christophe Boesch 《International journal of primatology》1995,16(2):1-16
Innovations of behavior have major implications for the concept of culture in animals. Innovation has rarefy been documented
in wild animal populations. The chimpanzees of the Ta? National Park, C?te d’Ivoire, spontaneously included new patterns of
behavior in their repertoire during our study. Some innovations were incorporated into a minority of the group members’ repertoire,
whereas others, such as building day nests in trees and on the ground more frequently, became general behaviors. Similarly,
new contexts for use of leaf- clipping behavior and novel ways of feeding on some leaves appeared and rapidly became part
of the behavior of most group members. The environmental parameters were too stable to explain these new forms of behavior,
as most of them took place within 1 month during the same dry season. In a similar way, leaf- grooming acquired a new function
in Gombe chimpanzees. A process similar to social conventions could explain the emergence of these new functions for an existing
behavior in a way rather similar to human “fashion. ” Three major characteristics of human culture — the absence of individual
variations in the performance of the behavior, the general use of the behavior by group members, and the ability to modify
the function of a behavior — characterize leaf-clipping in Ta? chimpanzees and leaf- grooming in Gombe chimpanzees. 相似文献
32.
Daniel Vittet Christophe Duperray Claude Chevillard 《Journal of cellular physiology》1995,163(3):645-655
Intracellular signaling processes by which hematopoietic growth factors regulate megakaryocytopoiesis remain uncompletely understood. Cyclic AMP (cAMP) has been shown to be implicated in the regulation of growth and differentiation in various normal and malignant cell types. Since a few studies have suggested the possible involvement of the cAMP pathway as one of the intracellular mechanisms whereby megakaryocytopoiesis may be regulated, we investigated the functional effects of cAMP on the human megakaryoblastic Dami cell line. We observed that exposure of Dami cells to cAMP analogs or to agents elevating intracellular cAMP levels yielded dose-dependent cell growth inhibition. Cell cycle progression analysis of cells predominantly synchronized at the G1/S boundary by prior treatment with hydroxyurea revealed that cAMP transiently accumulated cells in the G2/M phase, then slowing down cell cycle. On the other hand, immunofluorescence and Northern blot analysis of megakaryocytic differentiation marker expression showed that probes we have used significantly inhibited GPlb expression. Moreover, although these agents used alone did not affect GPllb/llla expression, they markedly reversed phorbol ester-induced GPllb/llla expression increase. These inhibitory cAMP actions on glycoprotein expression were not the result of cell cycle perturbation since we observed that GPlb and GPllb/llla expression were not cell cycle dependent. All these data may then be consistent with a potential negative regulatory role of the cAMP intracellular signaling pathway during megakaryocytopoiesis. © 1995 Wiley-Liss, Inc. 相似文献
33.
34.
Mathematical modeling and in-situ pH measurements were used to characterize the effects of the microenvironment on alginate gel beads immobilized cells of Lactococcus lactis. Mass transfer limitations led to a progressive pH acidification within gel beads which determined both the cell distribution and the cellular activity of entrapped cells. The dynamics of the system is discussed in relation to the overall activity of the immobilized cell reactor. 相似文献
35.
Maitrot Henri Paquin Cline Lacroix Christophe Champagne Claude P. 《Biotechnology Techniques》1997,11(7):527-531
Bifidobacterium longum was immobilized in k-carrageenan/locust bean gum gel beads, and cultured in a medium containing Lactobacillus MRS broth and whey-permeate. The same beads were incubated for 5 successive batch fermentations and freeze-dried following mixing with a protective solution. Viable population in the beads increased from 8 3 10 7 to 4.7 3 10 10 cfu/g after three batch fermentations, but no further increase in viable cell population could be achieved in the last two fermentations. The freeze-dried culture contained 3 3 10 10 cfu/g with a survival rate of approximately 10%. Survival to freeze-drying of immobilized cells was as good as that of classical free-cell cultures. Stability of freeze-dried cultures during storage at minus 17, 4 and 20°C was not influenced by immobilization. 相似文献
36.
Distinct response of Medicago suspension cultures and roots to Nod factors and chitin oligomers in the elicitation of defense-related responses 总被引:2,自引:1,他引:1
Arnould Savouré Christophe Sallaud Joumana El-Turk José Zuanazzi Pascal Ratet Michael Schultze Adam Kondorosi Robert Esnault Eva Kondorosi 《The Plant journal : for cell and molecular biology》1997,11(2):277-287
The induction of plant defense-related responses by chitin oligomers and the Rhizobium meliloti lipo-chito-oligosaccharide nodulation signals (Nod factors) in Medicago cell cultures and roots was investigated by following the expression of genes encoding enzymes of the isoflavonoid biosynthetic pathway, such as chalcone synthase, chalcone reductase, isoflavone reductase, as well as genes encoding a pathogenesis-related protein and a peroxidase. In suspension-cultured cells, all genes except the peroxidase gene were induced by both the R. meliloti Nod factor NodRm-IV(C16:2,S) and chitin oligomers with a minimum of three sugar residues. However, activation of these genes was not elicited by the symbiotically inactive, desulfated NodRm-IV(C16:2). Moreover, the cells were more sensitive to the chitin oligosaccharides than to the Nod factor. Analysis of flavonoids in Medicago microcallus cultures revealed differences between cells treated with N -acetyl-chitotetraose and those treated with Nod factor and demonstrated increased production of the phytoalexin medicarpin in the presence of Nod factor. In Medicago roots, none of the tested genes was activated by the N -acetylchitotetraose, whereas the Nod factor at micro-molar concentration enhanced transient expression of the isoflavonoid biosynthetic genes. The differential responses to Nod factors and chitin oligomers suggest that Medicago cells possess distinct perception systems for these related molecules. 相似文献
37.
Ivan Laprevotte Sophie Brouillet Christophe Terzian Alain Hénaut 《Journal of molecular evolution》1997,44(2):214-225
A computer-assisted analysis was made of 24 complete nucleotide sequences selected from the vertebrate retroviruses to represent
the ten viral groups. The conclusions of this analysis extend and strengthen the previously made hypothesis on the Moloney
murine leukemia virus: The evolution of the nucleotide sequence appears to have occurred mainly through at least three overlapping
levels of duplication: (1) The distributions of overrepresented (3–6)-mers are consistent with the universal rule of a trend
toward TG/CT excess and with the persistence of a certain degree of symmetry between the two strands of DNA. This suggests
one or several original tandemly repeated sequences and some inverted duplications. (2) The existence of two general core
consensuses at the level of these (3–6)-mers supports the hypothesis of a common evolutionary origin of vertebrate retroviruses.
Consensuses more specific to certain sequences are compatible with phylogenetic trees established independently. The consensuses
could correspond to intermediary evolutionary stages. (3) Most of the (3–6)-mers with a significantly higher than average
frequency appear to be internally repeated (with monomeric or oligomeric internal iterations) and seem to be at least partly
the cause of the bias observed by other researchers at the level of retroviral nucleotide composition. They suggest a third
evolutionary stage by slippage-like stepwise local duplications.
Received: 3 January 1996 / Accepted: 27 March 1996 相似文献
38.
Christophe Tournamille Caroline Le Van Kim Pierre Gane Jean-Pierre Cartron Yves Colin 《Human genetics》1995,95(4):407-410
Spondyloepiphyseal dysplasia tarda (SEDL) is an X-linked recessive disorder characterized in affected males by short stature resulting from a growth defect of the vertebral bodies. We have extended our earlier studies by analyzing 15 families with newly identified microsatellite DNA markers; analysis of recombination events with these markers indicates that the gene responsible for SEDL is located in Xp22 between DXS 16 and DXS 987 on an interval spanning approximately 2 Mb. 相似文献
39.
Christophe Philippe Ccile Arnould Frdrique Sloan Hans van Bokhoven Saskia D. van der Velde-Visser Michle Chery H. Hilger Ropers Simone Gilgenkrantz Anthony P. Monaco Frans P. M. Cremers 《Genomics》1995,27(3)
In a previous study, we have developed a panel of chromosomal rearrangements for the physical mapping of the q13-q21 region of the human X chromosome (Philippe et al., Genomics 17: 147-152, 1993). Here, we report the physical localization of 36 additional polymorphic markers by polymerase chain reaction analysis. The high density of chromosomal breakpoints in Xq21 allows us to map 58 DNA loci in 22 intervals. As a result, this segment of the X chromosome is saturated with approximately three sequence tagged sites per megabase of DNA, which will facilitate the construction of a YAC contig of this region. 相似文献
40.
A Vandermeers M C Vandermeers-Piret J Rathe J P Dehaye J Winand J Christophe 《Peptides》1984,5(2):359-365
Rat pancreatic acini were preincubated with 0.4 mM 32Pi for 45 min at 37 degrees C, then exposed for 15 min to VIP, secretin or CCK-8. The incubation was terminated with a stop solution and a fraction rich in mitochondria and zymogen granules was separated from a microsome-rich fraction by differential centrifugation. After heating in the presence of SDS, beta-mercaptoethanol was added and the pattern of equivalent amounts of 32P-labelled proteins was examined by autoradiography of SDS-PAGE gels. VIP, secretin, and CCK-8 stimulated the phosphorylation of a Mr=33 K microsomal protein and that of two proteins of Mr=21 K and Mr=25 K mostly present in a fraction rich in mitochondria and zymogen granules. Stimulations were dose-dependent, the highest stimulant concentrations tested allowing 2- to 3-fold increases of phosphorylation over basal. When 1 nM CCK-8 was used simultaneously with 1 microM VIP, the cyclic AMP levels attained and the pattern of protein phosphorylation were similar to those obtained with VIP alone, and there was a potentiation of amylase secretion; when a supra-maximal 0.1 microM CCK-8 concentration was added, the VIP-induced elevation in cyclic AMP levels and the phosphorylation of the Mr=21 K and Mr=25 K proteins were partially antagonized, and no potentiation any more of secretion occurred. To conclude the in vitro phosphorylation of three particulate proteins (Mr=33 K, 25 K, and 21 K) was similarly increased in rat pancreatic acini in response to secretin and VIP (acting through cyclic AMP) and to CCK-8 (acting mostly through Ca2+). 相似文献