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21.
22.
Are the characeae able to indicate the origin of groundwater in former river channels? 总被引:2,自引:0,他引:2
The macroscopic algae Characeae are usually assumed to occur in waterbodies supplied by groundwater with low phosphate content, but the indicative value of the species is seldom defined in bibliography. Former braided channels of the Rhône river are supplied with groundwater originating from the main channel (seepage) or from hillslope aquifer. The aim of the present paper was to determine if it possible to use the Characeae as indicators of physicochemical characteristies of water in order to assess the origin of groundwater supplying former river channels. Four former braided channels of the Rhône River colonized by Characeae were investigated, and the physico-chemical characteristics of i) the channels, ii) the groundwater and iii) the river were measured over a period of several months. Species are arranged along a gradient of conductivity, alkalinity, ammonium and phosphate content of the water. Charophyte species can indicate the origin of groundwater, either seepage or hillslope nutrient-poor aquifer, and integrate both the average value of the chemical parameter, and their variations. C. hispida occurs in a nutrient-poor channel mainly supplied by highly calcareous groundwater coming from hillslope aquifer. Chara major has requirements close to those of C. hispida, but is more tolerant to periodic inputs of nutrients. C. vulgaris and N. syncarpa both tolerate mesotrophic waters originating from both hillslope aquifer and seepage, and C. globularis is associated to a channel mainly supplied by mesotrophic to eutrophic river seepage. 相似文献
23.
Christophe Demaison Denis David Franck Letourneur Jacques Thèze Sentob Saragosti Moncef Zouali 《Immunogenetics》1995,42(5):342-352
Using CD19 B-cell selection and polymerase chain reaction-amplified cDNA libraries, we analyzed the peripheral immunoglobulin heavy chain variable repertoire of three healthy adult donors. Here we report that most of the CD19+ circulating B cells expressed unmutated V
H-D-JH rearrangements. By specific V
H family hybridization, we show that V
H gene family utilization in the periphery roughly corresponds to the complexity of these families in the germline and appears to be relatively constant among the analyzed subjects. However, sequence data of clones picked at random from one IgM cDNA library reveals that in spite of this random utilization, the V
H gene expression in naive circulating B cells is highly biased towards the expression of a limited set of V
H genes. As previously reported by others, this restricted mechanism is also found for the D and J
H segments.The nucleotide sequence data reported in this paper have been submitted to the GenBank/EMBL nucleotide sequence database and have been assigned the accession numbers Z47213-Z47243 and Z47349 相似文献
24.
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
25.
26.
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
27.
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
28.
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
29.
W J Malaisse M Svoboda S P Dufrane F Malaisse-Lagae J Christophe 《Biochemical and biophysical research communications》1984,124(1):190-196
Exposure of rat pancreatic islet membranes to [alpha-32P]-NAD+ in the presence of Bordetella Pertussis toxin (islet-activating protein) reveals the ADP-ribosylation of a peptide with a Mr close to 41 kDa, which corresponds to the alpha-subunit of the guanine nucleotide regulatory protein Ni. Islets removed from rats pretreated with the Bordetella Pertussis toxin display a specific increase in adenylate cyclase responsiveness to GTP and are characterized by a resistance to the inhibitory action of alpha2-adrenergic agonists upon either adenylate cyclase activity or glucose-induced insulin release. 相似文献
30.
Cyanide-sensitive O2 uptake was observed in the isolated embryonicaxis of soybean [Glycine max L. merr. cv. Essex]within 5 min after wetting and the O2 uptake rate during thefirst h of imbibition was directly proportional to axis moisturecontent. Within 10 min after wetting, O2 uptake was lower inaged low vigor (LV) axes than in high vigor (HV) axes imbibedeither in water (LV axes sustain imbibition injury) or in 30%w/v polyethylene glycol (LV axes do not sustain imbibition injury).Mitochondria isolated from LV axes after 4- and 24-h imbibitionwere characterized by lower O2 uptake, ADP:O, and respiratorycontrol ratios relative to HV mitochondria. A plot of O2 uptakevs temperature between 10 and 25?C revealed a break in the slopebetween 13 and 16?C for HV, but not LV, axes. Since LV axessustained water uptake injury at all temperatures tested, whereasHV axes sustained chilling injury only below 16?C, the dataindicate two temperature-O2 uptake relationships: one for injuredtissues and one for non-injured tissues. We conclude that deteriorationper se involves impairment of respiratory metabolism in thesoybean embryonic axis. Chilling (10?C; HV and LV axes) andimbibitional (25?C; LV axes) injuries during the initial minof inbibition further disrupt respiratory metabolism and interferewith subsequent mitochondrial development and axis growth.
1Scientific Articles No. A-3548, Contribution No. 6623 of theMaryland Agricultural Experiment Station. (Received May 25, 1983; Accepted September 28, 1983) 相似文献