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Showing papers by "University of Montpellier published in 1991"


Journal ArticleDOI
29 Aug 1991-Nature
TL;DR: It is shown that just two chains, the α and β associated chains, are sufficient to reconstitute an IgM surface receptor in fibroblasts and pro-pose that B-cell antigen receptors consist of a common α/β heterodimer associated with each immunoglobulin class.
Abstract: Several proteins associate with surface IgM to form the antigen receptor. We show that just two, the α and β associated chains, are sufficient to reconstitute an IgM surface receptor in fibroblasts. Contrary to expectation, α common a chain associ-ates with all five immunoglobulin classes. We pro-pose that B-cell antigen receptors consist of a common α/β heterodimer associated with each immunoglobulin class. But the classes differ both in the glycosylation of their associated α chain and in their dependence on α/β for surface transport.

295 citations


Journal ArticleDOI
14 Mar 1991-Nature
TL;DR: The results suggest that amplified esterase B2 genes originated from an initial event that has subsequently spread organophosphate insecticide resistance by migration, and that electrophoretically dissimilar esterases B varied considerably.
Abstract: IN Culex pipiens, overproduction of nonspecific esterases is a common mechanism of resistance to organophosphate insecticides1,2. The esterases are attributed to closely linked loci named A and B according to substrate preference3–6, and over-production of all esterases B is due to gene amplification7,8. Distribution of electrophoretically distinct variants of overproduced esterases A and B is geographically restricted, with the exception of esterases A2 and B2, always found together throughout at least three continents (Fig. 1). To determine whether this situation is due to migration or to a high mutation rate, esterase B structural genes and their flanking regions were compared by sequence and/or restriction fragment length polymorphism analysis. Whereas structural genes were similar, flanking regions of electrophoretically dissimilar esterases B varied considerably. In contrast, flanking sequences of esterases B2 from different geographical locations (Africa, Asia, North America) were identical. These results suggest that amplified esterase B2 genes originated from an initial event that has subsequently spread organophosphate insecticide resistance by migration.

287 citations


Journal ArticleDOI
TL;DR: In this article, the authors discuss the relation between phenolic compounds and polyphenoloxidase in relation to browning in grapes and wines, and present a review of their work.
Abstract: (1991). Phenolic compounds and polyphenoloxidase in relation to browning in grapes and wines. Critical Reviews in Food Science and Nutrition: Vol. 30, No. 4, pp. 441-486.

220 citations


Journal ArticleDOI
TL;DR: In this article, the Os isotopic compositions of twelve ultramafic and six mafic layer samples from the Ronda Ultramerafic Complex of southern Spain have been determined.

181 citations


Journal ArticleDOI
TL;DR: In this article, the interaction of grape seed procyanidin dimers and trimers, galloylated or not, with various proteins (poly-L-prolines, gelatins, casein, dried blood and grape arabinogalactan-protein) were studied in wine-like model solutions.
Abstract: Interactions of grape (Vitis vinifera L) seed procyanidin dimers and trimers, galloylated or not, with various proteins (poly-L-prolines, gelatins, casein, dried blood and grape arabinogalactan-protein) were studied in wine-like model solutions. Except for casein, protein-procyanidin complexes were produced within the first 8 h of contact. All poly-L-prolines presented very high affinity towards grape seed procyanidins. In general, the extent of pro-cyanidin-protein interaction increased with the degree of procyanidin polymerisation and the rate of galloylation, and also with protein concentration. When various protein fining treatments were applied to a young red wine, dimeric and trimeric procyanidin levels were not affected, although total phenolic levels were reduced.

167 citations



Proceedings ArticleDOI
01 Sep 1991
TL;DR: An object-oriented hypertext model (implemented in the MacWeb system) using structured types to incorporate knowledge in hypertext makes the capture of knowledge at source easier thus allowing a more conceptual navigation.
Abstract: It has been shown that the famous problem of user disorientation in hypertext is not due to the concept of hypertext itself but rather generally results from the lack of a conceptual model for hypertext application. Unfortunately, in most hypertext systems, the weakness of structure specification mechanisms discourages the development and use of such a model since it is difficult to reinforce hypertext structure and to really incorporate knowledge. A lot of works provide intelligent mechanisms to help navigation but either they use external knowledge or automatically synthesize links from information included in nodes which thereby have no sufficient conceptual value. The present paper focuses on an object-oriented hypertext model (implemented in the MacWeb system) using structured types to incorporate knowledge in hypertext. Concepts and their relationships as well as their instances and their own relationships may be represented. Such a model makes the capture of knowledge at source easier thus allowing a more conceptual navigation, Furthermore, active behaviors may be associated, as methods, to types. This provides a powerful mechanism to help develop structured hypertext as well as task centered applications, by taking advantage of knowledge representation.

135 citations


Journal ArticleDOI
TL;DR: Agar model gel cubes, with initial low solute content, were soaked in higher concentration solutions, and the influence of the concentration and molecular weight of the solute in the soaking solution, the temperature was observed as discussed by the authors.
Abstract: Agar model gel cubes, with initial low solute content, were soaked in higher concentration solutions. The influence of the concentration and molecular weight of the solute in the soaking solution, the temperature. the agar and solute content of the model food on water loss and solute gain rates were observed. The achievement of a prevailing dewatering effect with only marginal solute pick-up proved to be related to a inverse relationship between the cross-flows of water and solute, reinforced by shrinkage. As a preliminary to further modelling, reasonable assumptions were drawn from experimental result analysis.

130 citations


Journal ArticleDOI
TL;DR: Ability of postlarvae and adults to hyper-regulate in low-salinity media decreased after exposure to ammonia, and the presence of ammonia in the external medium could markedly affect the Na+/NH4+ transport mechanism by permanently, temporarily, or partially impair the transport sites for sodium.
Abstract: Acute toxicity of ammonia was determined for cultured larval, postlarval, and wild adult lobsters (Homarus americanus) in 1988. Ammonia tolerance was found to increase with ontogenetic development. Based on 96-h LC50 values of 58 mg l−1 NH4 + + NH3 l−1 seawater (0.72 mg NH3 l−1) for Stage I larvae, 87 mg NH4 + + NH3 l−1 (1.7 mg NH3 l−1) for Stage II larvae, 125 mg NH4 + + NH3 l−1 (2.13 mg NH3) for Stage III larvae, 144 mg NH4 + + NH3 l−1 (2.36 mg NH3 l−1) for Stage IV postlarvae, 377 mg NH4 + + NH3 l−1 (5.12 mg NH3 l−1) for adult lobsters at 5°C and 219 mg NH4 + + NH3 l−1 (3.25 mg NH3 l−1) for adult lobsters at 20°C, recommendations for “safe” levels of total ammonia and un-ionized ammonia were calculated using an application factor of 0.1. Effects of ammonia on osmoregulatory capacity were studied on postlarvae and adults. Ability of postlarvae and adults to hyper-regulate in low-salinity media decreased after exposure to ammonia. In postlarval lobsters, osmoregulatory capacity was significantly affected in ammonia concentrations exceeding 32 mg l−1. Osmoregulatory capacity in adult lobsters (5 and 20°C) was affected at 150 mg l−1. In postlarval lobsters, a minimum exposure time of 12 h was required to impair osmoregulatory capacity. The decrease in hemolymph osmotic pressure was caused by lower hemolymph sodium concentrations. The presence of ammonia in the external medium could markedly affect the Na+/NH4 + transport mechanism by permanently, temporarily, or partially impairing the transport sites for sodium.

124 citations


Journal ArticleDOI
01 Apr 1991-Lithos
TL;DR: In this paper, an upwelling mantle structure of the Oman ophiolite (Maqsad diapir), in undeformed dunites displaying evidence for magma impregnation and circulation, just below the paleo-ridge axis.

121 citations


Journal ArticleDOI
TL;DR: The resistance of poplar cultivars to mistletoe was dependent on the production of defensive mechanisms against the pathogen, and these reactions were weaker in the FPL cultivar than in the VER one.
Abstract: Flavonoid compounds were studied in healthy and parasitized poplar branches following mistletoe (Viscum album L.) attack. Two poplar cultivars showing different degrees of resistance to mistletoe: sensitive “Fritzi Pauley” (FPL) and resistant “Vereecken” (VER) were used. Flavonoids were detected and localized using histofluorescence after treating frozen sections with two specific reagents. Total amounts of flavonoids were determined spectrophotometrically. Defence mechanisms were induced during penetration of the primary haustorium. They consisted of inner periderm development and flavonoid accumulation. These reactions were weaker in the FPL cultivar than in the VER one. In the latter, growth of the primary haustorium and the establishment of direct connections between the living host cells and parasite failed. The resistance of poplar cultivars to mistletoe was dependent on the production of defensive mechanisms against the pathogen.

Journal ArticleDOI
TL;DR: Results from the present study strongly suggest a differential involvement of the hypothalamic noradrenergic innervation upon the hypothalamus-pituitary-adrenal axis according to the nature of stress conditions.
Abstract: The aim of the present study was to explore in male rats the role of the catecholaminergic innervation of the hypothalamus in corticotropic and adrenal responses to different kinds of stress conditions. For this purpose, 6-hydroxydopamine (3 μg in 0.2 μl saline) was stereotaxically and bilaterally infused at two levels of the main noradrenergic ascending brain stem bundle (NAB-X). The efficiency of catecholaminergic denervation of the hypothalamus was checked by measuring noradrenaline concentrations in paraventricular nuclei punches by HPLC and was confirmed by a 86% fall in noradrenaline levels of NAB-X rats killed after the stress experiments. Seven days after lesioning the NAB, sham operated controls and NAB-X lesioned animals were divided into 4 groups and submitted to 4 different stressors, i.e.: 2 min ether vapors (n = 5), 1 h immobilization (n = 7), i.v. histamine (2 mg/kg; n = 7) or i.v. insuline (10 I.U./kg; n = 8) injections. ACTH and corticosterone were measured in blood samples sequentially taken from a chronic carotid cannula, before stress and at short intervals over the 2 following hours. In comparison to the respective control groups, NAB-X dramatically reduced the ACTH response to ether (-78%) and to restraint (-53%) stress whereas the corticosterone response was affected to a lesser extent. In contrast, NAB-X slightly altered these responses in the histamine-treated group, although, surprisingly, the ACTH response tended to decrease and that of corticosterone to increase. Finally, NAB-X provoked a biphasic response to insulineinduced hypoglycemia, with a very early (5 min) rise in ACTH and corticosterone in comparison to the control group, followed by a trend to low hormonal levels up to 120 min. These results strongly suggest a differential involvement of the hypothalamic noradrenergic innervation upon the hypothalamic-pituitary-adrenal axis according to the nature of stress conditions.

Journal ArticleDOI
TL;DR: The development of intestinal lipid absorption capacities was studied in larvae of the sea bass Dicentrarchus labrax from the time of mouth opening to 25 d after hatching, in individuals fed with brine shrimp, Artemia sp.
Abstract: The development of intestinal lipid absorption capacities was studied in larvae of the sea bassDicentrarchus labrax from the time of mouth opening to 25 d after hatching, in individuals fed with brine shrimp,Artemia sp. (Brazil commercial strain) or artificial diets. At the time of mouth opening, before the first feed, enterocytes synthesized lipoprotein particles from endogenous lipids. Starting with the first feed, enterocytes absorbed food lipids regardless of the diet, but since these cells have a low capacity for lipoprotein synthesis, they accumulated lipids in the form of “free” lipid droplets. In larvae fed withArtemia sp., the rapid development of enterocytes during growth was combined with increasingly effective lipoprotein synthesis (becoming even greater than that observed in the adult), starting on Days 18 to 19. Although lipoprotein synthesis and transport were observed in larvae given artificial feed, they showed abnormalities in their intestinal mucosa. Lipid droplets formed in association with the membrane structures of specimens given egg yolk during the first days of feeding, and enterocytes degenerated. In 18 to 19 d-old larvae given artificial feed, intestinal folds disappeared and the constituent cells showed limited differentiation. In the last-mentioned individuals, the abnormalities appeared to be related to malnutrition resulting from inadequacy of the food offered, which led to total mortality of larvae, beginning on Day 20.

Journal ArticleDOI
TL;DR: Some of the cochlear damage that occur with ageing, especially the loss of the radial afferent fibres and type I ganglion cells, might well be attributed to glutamate excitotoxicity linked to vascular atrophy.
Abstract: Glutamate is considered to be one of the most common neurotransmitters in the fast excitatory synapses in the central nervous system. On the other hand, its excitotoxic properties are increasingly cited to explain some of the brain damage linked with hypoxia and ischaemia: i.e., those that occur frequently in ageing. An excess release of glutamate could, either directly or indirectly, activate receptors on the postsynaptic neuron, causing ion influxes accompanied by a massive entry of water, which would lead to an acute swelling of dendrites. In addition, calcium influx deregulates calcium homeostasis, which could lead to cell death. In the cochlea, glutamate is now considered to be one of the best candidates to mediate neurotransmission between inner hair cells (IHCs) and the auditory nerve dendrites. Among the variety of anatomical and physiological findings supporting the glutamate hypothesis, is the striking similarity of acute damage in the organ of Corti caused by exposure to a glutamate analogue (kainic acid), or by hypoxia, or even by an intense loud noise. In all cases an immediate swelling is observed, specifically affecting the radial afferents below the IHCs. The best explanation for this swelling is related to glutamate (or glutamate analogue) excitotoxicity. Thus, some of the cochlear damage that occur with ageing, especially the loss of the radial afferent fibres and type I ganglion cells, might well be attributed to glutamate excitotoxicity linked to vascular atrophy. The present paper discusses this hypothesis.

Journal ArticleDOI
TL;DR: ‘Laboratoire de Parasitologie Cornparke, (URA 698, CNRS).
Abstract: ‘Laboratoire de Parasitologie Cornparke, (URA 698, CNRS). UniversitP de Montpellier II. PI. E Bataillon; 34095 Montpellier cedex 5; FRANCE. ‘Institut des Sciences de I’Ecolution, “GPnome et Population”, (URA 327 CNRS). UnitlersitP de Montpellier II. PI. E. Bataillon; 34095 Montpeflier cedex 5; FRANCE. ‘Department of Molecular Biology and Plant Physiology. UnicersitJt of Aarhus. C. F. M&en AlIP 130. DK-8000; Aarhus, DENMARK

Proceedings ArticleDOI
19 Jun 1991
TL;DR: In this paper, a new design for a six-degree-of-freedom (DOF) parallel structure dedicated to high-speed applications is presented, where the authors extend the principle of the DELTA mechanical structure in order to obtain orientations of the travelling plate.
Abstract: The paper presents a new design for a six-degree-of-freedom (DOF) parallel structure dedicated to high-speed applications. The authors extend the principle of the DELTA mechanical structure in order to obtain orientations of the travelling plate. The approach which goes from the DELTA to the HEXA is first developed. Then a kinematic model of the HEXA is proposed. Finally a dynamic model of that robot is presented. >

Journal ArticleDOI
TL;DR: The results suggest the presence of N-methyl-D-aspartate receptors in the cochlea, namely the glutamatergic receptors located on the auditory nerve dendrites contacting the inner hair cells.


Journal ArticleDOI
TL;DR: This paper summarizes the most recent findings dealing with the anatomical development of the human cochlea, and especially with ultrastructural data from both scanning and transmission electron microscopic studies.
Abstract: This paper summarizes the most recent findings dealing with the anatomical development of the human cochlea, and especially with ultrastructural data from both scanning and transmission electron microscopic studies. It also briefly reviews physiological findings and attempts to specify the timing of the main developmental events, i.e. the onset of function, the acquisition of adult properties, and the sensitive periods.

Book ChapterDOI
01 Jan 1991
TL;DR: In this article, the distribution of noble metals in ophiolitic complexes is discussed and new targets for exploration are suggested, and a review paper is presented to discuss the distribution.
Abstract: This review paper attempts to discuss the distribution of noble metals in ophiolitic complexes and suggests new targets for exploration.

Journal ArticleDOI
TL;DR: Serial section analysis indicates that expression of the HCA is always limited to areas of the epithelium where nerve fibres are found, although the delay between the onset of innervation and the onsetof HCA expression varies from one region of the otocyst to another.
Abstract: The 275 kD hair-cell antigen (HCA) is a protein that was originally identified using immunological techniques in the inner ears of early hatchling and adult chickens. The HCA is specifically associated with the apical surface of sensory hair cells; in the vestibular system the antigen is distributed over the entire stereocilia bundle, but in the auditory system it only extends a short distance up the shafts of the stereocilia. The objectives of this study were to ascertain when the HCA is first expressed during inner ear development, to compare the temporal and spatial patterns of HCA expression with those of neurite ingrowth, and to determine how the distribution of the antigen observed in the auditory system arises during development. Serial sections of otocysts from embryonic day (ED) 4 to ED7.5 (stages 24 to 32) were stained with a monoclonal antibody to the HCA and polyclonal antibodies to the neuron–glial cell adhesion molecule in order to analyse patterns of HCA expression and neurite ingrowth. Nerve fibres are first observed in the anterior pole of the otocyst at ED4.5 (stage 24), and in the evaginating basilar papilla by EDS (stage 26). The HCA first appears within the vestibular system in the anterior pole of the otocyst at EDS (stage 26), and within the auditory system in the distal end of the basilar papilla at ED6.5 (stage 29). Serial section analysis indicates that expression of the HCA is always limited to areas of the epithelium where nerve fibres are found, although the delay between the onset of innervation and the onset of HCA expression varies from one region of the otocyst to another. The growth of stereocilia bundles in the auditory system was studied from ED10 to 2 days after hatching in sections from the medial to distal regions of the basilar papilla double labelled with rhodamine phalloidin and monoclonal anti-HCA, At ED12 the stereocilia bundles are 1.7 μm high and the staining observed with both phalloidin and the antibody extend to the same maximum height above the apical surface of the hair cell. The maximum height that anti-HCA staining extends up the stereocilia bundle remains almost constant between ED12 and postnatal day 2, but between ED15 and ED18 the stereocilia bundle grows rapidly in height, with a membrane domain lacking the HCA forming at the distal ends of the stereocilia. The restricted distribution of the HCA observed on the apical surface of mature auditory hair cells in the basilar papilla is therefore generated during the final growth phase of the stereocilia bundle by the accumulation of HCA-free membrane at the distal ends of the stereocilia.

Journal ArticleDOI
TL;DR: Aluminium titanate has a near zero thermal expansion coefficient (α=0.8×10−6 °C−1) in the range 20 to 1000 °C, nevertheless it decomposes below 1200 °C as mentioned in this paper.
Abstract: Aluminium titanate has a near zero thermal expansion coefficient (α=0.8×10−6 °C−1) in the range 20 to 1000 °C, nevertheless it decomposes below 1200 °C.

Journal ArticleDOI
TL;DR: In this paper, the relationship of the dilatation of a gel to its permeability and modulus is analyzed, allowing for syneresis of the gel network, and it is shown that expansion can be observed during heating at 0.5°C/min with total temperature changes of ∼ 5°C.
Abstract: When a gel is heated, the thermal expansion of the pore liquid causes stretching of the solid network. If the heating rate is very high, the gel expands at the same rate as the liquid; at slower rates, some of the liquid drains out and the gel expands less. By measuring the axial deformation of a gel rod, it is possible to determine the elastic relaxation time, which involves the product of the permeability, D , and the elastic modulus of the gel. Using independently measured elastic properties, one readily obtains D . This method is ideally suited for compliant gels for which more direct methods of measurement of D are difficult. In this paper an analysis of the problem is presented showing the relationship of the dilatation of a gel to its permeability and modulus, allowing for syneresis of the gel network. Experimental data are presented for a 2-step base-catalyzed silica gel, showing that expansion can readily be observed during heating at 0.5°C/min with total temperature changes of ∼ 5°C. The permeability determined from this experiment is in good agreement with that obtained previously by a more difficult method.

Journal ArticleDOI
TL;DR: A genetic study carried out on nine natural mussel populations on the French Atlantic coast from 1989–1990 revealed interdigitation between typicallyMytilus edulis and typicallyM.
Abstract: A genetic study carried out on nine natural mussel populations on the French Atlantic coast from 1989–1990 revealed interdigitation between typicallyMytilus edulis and typicallyM. galloprovincialis populations and intermediate populations. The allele components of the populations followed aM. edulis/M. galloprovincialis gradient which does not correspond to a geographical gradient. Strong hybridization was evident in samples with intermediate allele frequencies. The respective importance of gene flow and selection is discussed in the light of the results and the evironmental features of the sampling zone.

Journal ArticleDOI
TL;DR: The relative role of selfing and outcrossing in the evolution of freshwater snail populations is discussed and a striking difference was shown in favor of cross‐fertilization for the number of eggs laid, the survival at birth of young snails and the numberof snails reaching sexual maturity.
Abstract: Self-fertilization depression of fitness in the freshwater hermaphroditic snail Bulinus globosus, an intermediate host of the parasitic trematode Schistosoma, has been studied in a strain originating from Niger. B. globosus is an outcrosser that can self-fertilize when isolated before any copulation has occurred. The self-fertilization depression has been estimated during two successive generations. In the first generation, selfing was compared to outcrossing. Within each mating system group, selfing and outcrossing were compared again in the second generation. A striking difference was shown in favor of cross-fertilization for the number of eggs laid, the survival at birth of young snails and the number of snails reaching sexual maturity. The overall self-fertilization depression is 0.920 after two generations of selfing. We discuss the relative role of selfing and outcrossing in the evolution of freshwater snail populations.

Journal ArticleDOI
TL;DR: Cheese analogs were prepared from calcium caseinate, butter oil and emulsifying sodium salts (ES), and increasing ES levels gave cheese analogs with higher pH, degree of casein dissociation and degree of fat emulsification than the control without ES as discussed by the authors.
Abstract: Cheese analogs were prepared from calcium caseinate, butter oil and emulsifying sodium salts (ES). Increasing ES levels gave cheese analogs with higher pH, degree of casein dissociation and degree of fat emulsification than the control without ES. Firmness of cheese analogs first increased, then decreased when the ES level was increased from 1 to 3%. Effects depended on the degree of polymerization of phosphate salts. Sodium citrate (>1%) or Na2HPO4 (>2%) made cheese analogs more able to melt upon reheating. Melting ability correlated with high pH, soft texture, high degree of casein dissociation and low degree of fat emulsification.

Journal ArticleDOI
01 Nov 1991-Nature
TL;DR: In this paper, the electrical resistivity of solid granular C60 up to pressures of 25 GPa was measured and it was shown that the magnitude of the gap and the resistivity decrease with increasing pressures as the sample volume decreases.
Abstract: THE bonding between molecules in bulk solid C60 is extremely weak, making it a narrow-band semiconductor with an energy gap of 1.5 eV (ref. 1) for the face-centred cubic phase. Doping with alkali metals produces a metallic state which can be superconducting at temperatures as high as 33 K (ref. 2). The intermolecular coupling should have an important influence on the conductivity of the pure, semiconducting state: stronger coupling might induce a transition to a metallic or possibly even superconducting state, as is the case for silicon3, or it may result in a covalent solid such as diamond4. We have explored these possibilities by measuring the electrical resistivity of solid granular C60 up to pressures of 25 GPa. Our results show that the magnitude of the gap and the resistivity decrease with increasing pressures as the sample volume5 decreases. But eventual gap closure to give a metallic state is not observed; instead, there is a sudden transition at 15–20 GPa to a more insulating phase, possibly with covalent intermolecular bonding.

Journal ArticleDOI
TL;DR: The pyrolysis of liquid or solid polyvinylsilazanes, cross-linked according to four different routes, was studied in the 20-1400°C temperature range.
Abstract: The pyrolysis of liquid or solid polyvinylsilazanes, cross-linked according to four different routes, was studied in the 20–1400°C temperature range. The similar behaviour and the high ceramic yields (⋍85%) are related to the reactivity of the functional groups (CHCH2, SiH, NH) which lead to highly cross-linked solids before the mineralization step. The major gases evolved above 450°C are hydrogen, methane and ethylene. During the thermal treatment SiN bonds are unaffected. The silicon carbonitride samples are dense and amorphous up to 1400°C. The thermal stability of the microtexture is due to the high carbon content.

Journal ArticleDOI
TL;DR: Les Malines Mine (Cevennes, France) provides an example of Pb-Zn ore bodies that underwent a polyphased evolution as mentioned in this paper, where experimental points of the Les Malines ore types always plot in the central part of the field defined for the Cevennes metallogenic province.
Abstract: Les Malines Mine (Cevennes, France) provides an example of Pb-Zn ore bodies that underwent a polyphased evolution. On the Pb-Pb diagram, experimental points of the Les Malines ore types always plot in the central part of the field defined for the Cevennes metallogenic province. This homogeneity, the similarities with the Pb isotopic compositions of the surrounding rocks and the comparison with Pb isotopes evolution of whole rocks and minerals of the neighbouring continental lands, which emerged during Triassic and Liassic times, rule out the participation of extraneous Pb during the successive concentration stages and agree with an initial metal stock transformed and mobilized in a Pb closed system. Hercynian K-feldspars are the main source of the Pb preconcentrated during Triassic times. Most of the Cevennes Pb-Zn ore bodies could derive from this Triassic metal stock; nevertheless, local Pb isotopic anomalies suggest hydrothermal sources for some Pb-Zn ore bodies located along the Cevennes fault.