Papers by Joseph Schrével
Experimental Parasitology, 1996
SUMMARY The freeze-cleave technique demonstrates the presence of gap junctions at early stages of... more SUMMARY The freeze-cleave technique demonstrates the presence of gap junctions at early stages of mouse cardiac muscle ontogenesis. The formation and growth of these junctions were studied at 4 stages of development: 10, 14, 18 days post-coitum (dpc) and at the adult stage. The diverse aspects of the gap junctions are interpreted as different steps in their formation. The first
Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1973
ABSTRACT 1.1. Storage polysaccharide bodies in trophozoites of Gregarina blaberae have been studi... more ABSTRACT 1.1. Storage polysaccharide bodies in trophozoites of Gregarina blaberae have been studied using light and electron microscopy. The bodies, which grow to at least 6 μm, show a dark cross phenomenon in polarized light microscopy.2.2. Chemical and enzymic investigations indicate that the storage polysaccharide of G. blaberae is an amylopectin with an average chain length of about nineteen glucose residues, and with properties closely resembling the amylopectin from the coccidia Eimeria tenella.3.3. The fine structure of the storage polysaccharide has been studied using a debranching enzyme from Cytophaga. The unit chain profile of the debranched polysaccharide is intermediate between a plant amylopectin and an animal glycogen and is similar to that of sweet corn phytoglycogen.
The Journal of Protozoology, 1971
ABSTRACT SYNOPSIS. The taxonomic position of Selenidiidae Brasil in the class of gregarines is di... more ABSTRACT SYNOPSIS. The taxonomic position of Selenidiidae Brasil in the class of gregarines is discussed in relation to the study of its life cycles, its possible schizogony and the fine structure of its trophozoites. The cycle of gregarines which belong to the genus Selenidium Giard is characterized by trophozoites with pendular or coiling movements, nuclear transformations in gamonts during syzygy just before cyst formation, anisogamy, sporocysts with 4 sporozoites. Schizogony of the Selenidiidae is not yet demonstrated. The “kystes á meérozoites” within the gut epithelium of Sabellaria alveolata, could be one of the stages of schizogony of S. hollandei. This sole example in our study and the absence of schizogony in numerous species, especially in S. pendula, the type species, shows that this criterion is uncertain, actually, in the definition of the order Archigregarinida Grassé. Ultrastructural studies of S. hollandei and S. pendula show that the cortical region in trophozoites of the genus Selenidium is different from that of Eugregarinida. In the Selenidiidae the epicyte is composed of longitudinal folds. Under the wall, consisting of 3 membranes there is a well-defined pellicular fibrillar system. In S. hollandei, the trophozoite has a fibrillar formation, corresponding to a conoid in its anterior region. The trophozoites of S. hollandei and S. pendula contain anterior dense bodies or rhoptries which are very well developed. All these characteristics conform to the ultrastructural organization of the dissemination forms (merozoites, schizozoites, sporozoites): The results allow one to give a new definition of the Order Archigregarinida: Order Archigregarinida (Grassé): Gregarines with ultrastructural organization of the trophozoites similar to that of dissemination forms. Presence of a well defined pellicular fibrillar system. Intestinal parasites of polychaete worms.
Cell Motility, 1982
The male gametes of the parasitic protozoan, Lecudina tuzetae, have a motile flagellum with a "6 ... more The male gametes of the parasitic protozoan, Lecudina tuzetae, have a motile flagellum with a "6 + 0" ultrastructure [Schrkvel and Besse, 19751. These gametes were isolated from the cysts in which they develop and were observed and photographed under a variety of conditions. The flagella beat continuously, without stopping and starting, with a beat period of about 2 sec. They can beat in solutions whose viscosities are greater than 0.5 Nsm-' (1 Nsm-' = lo3 cP). The waveform can be approximated by a series of helical arcs and interconnecting straight regions that travel from the base to the tip. The helical regions have a radius of curvature of 3 . 2 pm and subtend a final angle of 1.7 radians. The straight portions are 2.0 pm in length. There are two sets of opposing bends, but they do not originate in the same plane. The resulting waveform is an approximately helical coil, with a pitch of 9.8 pm, a pitch angle of 0.6 radian and a peak-to-peak amplitude of 2.3 pm. The sense of the coil is left handed. The axoneme twists during beating. The main differences between the movement of this flagellum and that of typical 9 + 2 flagella are a low beat frequency and three-dimensional bends that produce relatively little forward movement of the cell. Twisting is discussed as a means of discriminating between some types of models of flagellar motility.
The Journal of Protozoology, 1977
ABSTRACT RESUME. L' étude ultrastructurale de la grégarine Gregarina blaberae a été entre... more ABSTRACT RESUME. L' étude ultrastructurale de la grégarine Gregarina blaberae a été entreprise après mise au point d'un protocole d'infestation expérimentale de larves vierges de Blattes, Blaberus craniifer. Les observations en microscopie électronique, effectuées en fonction du temps, ont permis de suivre le développement du sporozoïte, ainsi que la croissance et l' évolution du trophozoïte.La croissance est spectaculaire puisqu'en 18 jours elle entraîne la transformation du germe infectieux ou sporozoïte (L = 15 μm, φ=1 μm) en un céphalin—trophozoïte fixéà l' épithélium intestinal—de 250 μm de longueur pour un diamètre de 65 μm. L'organisation ultrastructurale du sporozoïte ne diffère pas de celle de la plupart des sporozoïtes des autres sporozoaires étudiés jusqu' à présent, le conoïde et les corps denses sont présents. La paroi est trimembranaire. toutefois le complexe membranaire interne présente quelques interruptions. Les premiers dictyosomes s' élaborent à partir de l'enveloppe nucléaire. La migration du noyau et des corps denses, puis la régression de toutes les formations caractéristiques du sporozoïte et l' établissement d'une zone corticale venant coiffer l' épimérite, ont lieu dans les 48 heures suivant l'infestation et marquent la transformation sporozoïte-céphalin.L' évolution du céphalin, se poursuit par la formation des ébauches des plis épicytaires qui s'effectue à partir du 3éme jour du développement à la base du deutomérite. Un système régulier de plis longitudinaux ou épicyte s' établit ainsi sur toute la partie extra-cellulaire de la grégarine. Dès les 4éme-5éme jours de développement, un réseau vacuolaire et un chondriome important se différencient dans l' épimérite, tandis qu'un septum de nature fibrillaire isole le protomérite du deutomérite. Le stade suivant—à partir du 6éme jour—est marqué par une ségrégation du matériel glucidique au niveau de ces 2 segments.Le modèle étudié permet de préciser le rôle de l' épimérite dansla nutrition du parasite, l' évolution du chondriome et des membranes corticales au cours de la phase de croissance végétative des grégarines polycystidées.SYNOPSIS. In an ultrastructural study the development of the sporozoite as well as the growth and development of the trophozoite of Gregarina blaberae were followed in the course of experimental infections of larvae of the cockroach Blaberus craniifer.The spectacular growth involved the transformation within 18 days of the sporozoite, measuring 15 × 1 μm, to a cephaline—trophozoite affixed to the intestinal epithelium—of 250 μm length and 65 μm diameter. The sporozoite's ultrastructure is not different from that of sporozoites of other Sporozoa studied to date—the conoid and dense bodies are present. The pellicle consists of 3 membranes, but there are some interruptions in the internal membrane complex. The first dictyosomes are formed from the nuclear envelope. The migration of the nucleus and of the dense bodies, followed by the regression of all the structures characteristic of the sporozoites, and the establishment of a cortical zone that comes to cover the epimerite, take place within 48 hr after infection and mark the transformation of the sporozoite into the trophozoite.Development of the cephaline involves the formation of the epicytic folds, which occurs at the base of the deutomerite, starting on the 3rd day of development. A regular system of longitudinal or epicytic folds is formed over the entire surface of the gregarine. On the 4th and 5th days of development, a vacuolar system and a chondriome become differentiated in the epimerite, while a fibrillar septum separates the protomerite from the deutomerite. The next stage, starting on the 6th day, is characterized by distribution of polysaccharide reserves between these 2 segments.The model studied allows us to determine the role of the epimerite in the parasite's nutrition, as well as the development of the chondriome and of the cortical membranes in the course of the vegetative growth phase of the cephaline gregarine.
Infection and immunity, Jan 30, 2015
We have previously shown that secreted phospholipases A2 (sPLA2s) from animal venoms inhibit the ... more We have previously shown that secreted phospholipases A2 (sPLA2s) from animal venoms inhibit the in vitro development of P. falciparum, the agent of malaria. In addition, the inflammatory-type human group IIA (hGIIA) sPLA2 circulates at high levels in the serum of malaria patients. However, the role of the different human sPLA2s in host defense against P. falciparum has not been investigated. We show here that 4 out of 10 human sPLA2s, namely hGX, hGIIF, hGIII and hGV, exhibit potent in vitro anti-Plasmodium properties with IC50 values of 2.9±2.4, 10.7±2.1, 16.5±9.7 and 94.2±41.9 nM, respectively. Other human sPLA2s including hGIIA are inactive. The inhibition is dependent on sPLA2 catalytic activity and primarily due to hydrolysis of plasma lipoproteins from the parasite culture. Accordingly, purified lipoproteins that have been pre-hydrolyzed by hGX, hGIIF, hGIII and hGV are more toxic to P. falciparum than native lipoproteins. However, the total enzymatic activities of human sPLA...
Parasitology today (Personal ed.), 1998
Cell motility and the cytoskeleton, 2005
Lecudina tuzetae is a parasitic protozoan (Gregarine, Apicomplexa) living in the intestine of a m... more Lecudina tuzetae is a parasitic protozoan (Gregarine, Apicomplexa) living in the intestine of a marine polychaete annelid, Nereis diversicolor. Using electron and fluorescence microscopy, we have characterized the dynamic changes in microtubule organization during the sexual phase of the life cycle. The gametocyst excreted from the host worm into seawater consists of two (one male and one female) gamonts in which cortical microtubule arrays are discernible. Each gamont undergoes multiple nuclear divisions without cytokinesis, resulting in the formation of large multinucleate haploid cells. After cellularization, approximately 1000 individual gametes are produced from each gamont within 24 h. Female gametes are spherical and contain interphase cytoplasmic microtubule arrays emanating from a gamma-tubulin-containing site. In male gametes, both interphase microtubules and a flagellum with "6 + 0" axonemal microtubules extend from the same microtubule-organizing site. At the b...
Cell motility and the cytoskeleton, 1999
Vinca alkaloids, vincristine and vinblastine, produce differential effects on the cell division o... more Vinca alkaloids, vincristine and vinblastine, produce differential effects on the cell division of Trypanosoma cruzi epimastigote forms depending on drug concentrations. These effects are related to different microtubule-based mechanisms. For 15 microM vinblastine and 50 microM vincristine, the drugs inhibit both nuclear division and cytokinesis, and affect cell shape. At 3 microM vinblastine and 10 microM vincristine, however, cytokinesis is inhibited without major effect on the progression of the cell cycle; this yields giant cells having multiple nuclei, kinetoplasts and flagella. Cultures maintained over 1 week with daily drug replacement produced cells with more than 16 nuclei and 24 kinetoplasts, indicating that an equivalent of a fifth cell cycle was initiated. The ultrastructure of the multinucleate cells showed a basic organization closely similar to that of trypanosomes. Cytokinesis inhibition by vinca alkaloids seems to result from modulations of interactions between micr...
Clinical hemorheology and microcirculation, 1998
Photochemical methods using photosensitizing photoactive drugs are very promising for blood produ... more Photochemical methods using photosensitizing photoactive drugs are very promising for blood product decontamination. Depending on the nature of virus - or parasite - bound photosensitizers, direct photochemical addition to virus components (DNA, proteins and lipids) occurs or the photosensitizer produces singlet oxygen inactivating viruses or parasites. The main advantage of this method is the lack of dark toxicity of presently used photosensitizers (psoralens, methylene blue, merocyanine 540, porphyrins/chlorins, phthalocyanines). In blood, the uptake of photosensitizers is not fully specific for infected cells. Therefore, normal cells and plasma proteins may suffer from the photodynamic action. Consequently, cell metabolism, rheological properties and surface markers may be altered and a slow loss of functionality occurs during storage. Data regarding pathogen inactivation in plasma and blood proteins, platelets and RBC concentrates are presented in comparison with the effect of p...
Antimicrobial agents and chemotherapy, 1996
The stage-dependent susceptibility of Plasmodium falciparum to a short exposure to docetaxel (Tax... more The stage-dependent susceptibility of Plasmodium falciparum to a short exposure to docetaxel (Taxotere) was evaluated by subjecting ring-infected, trophozoite-infected, and schizont-infected erythrocytes to a 5-h exposure to various concentrations of the drug. The schizont stage was shown to be the most sensitive stage; an inhibition of more than 60% of parasite development was observed at 10 nM. At this drug concentration, the development of the younger ring and trophozoite forms was unaffected. The in vivo antimalarial activity of docetaxel against the development in blood of old trophozoites of a species that causes malaria in rodents, Plasmodium vinckei petteri, was evaluated in IOPS-OF1 mice. Two tests were performed: the 4-day suppressive test, as described by Peters (W. Peters, p. 145-273, in Chemotherapy, and Drug Resistance in Malaria, vol. 1, 1987), and the effects of a single injection of docetaxel after inoculation of the parasites. A single injection of docetaxel at 40 ...
Infection and immunity, 1993
Previous results with the Babesia divergens gerbil vaccination model were extended in studies wit... more Previous results with the Babesia divergens gerbil vaccination model were extended in studies with cattle. Two calves were vaccinated with culture-derived B. divergens exoantigens, and two others were treated with control supernatant; both preparations were adjuvanted with Quil-A saponin. A parasite-specific humoral response was observed after the first vaccine injection and was boosted by two succeeding vaccine injections. Sera from the two vaccinated calves immunoprecipitated eight major parasitic proteins (with molecular masses ranging between 17 and 110 kDa) whose patterns were close to those observed in gerbil vaccine assays. The cellular immune response, monitored by lymphoproliferation assays, was slightly delayed in comparison with the humoral response; a significant proliferation occurred only after the second vaccine injection. Mononuclear cell proliferation was dose dependent in the presence of (i) lysates of B. divergens-parasitized erythrocytes, (ii) exoantigens of the ...
Biochemistry international, 1986
Trimethylamino-diphenylhexatriene (TMA-DPH), a novel hydrophobic fluorescent probe with relevant ... more Trimethylamino-diphenylhexatriene (TMA-DPH), a novel hydrophobic fluorescent probe with relevant photophysical properties for fluorescence anisotropy measurements in phospholipidic membranes, specifically labels the plasma membranes of whole living-cells, unlike earlier commonly used probes such as 1,6-diphenyl-1,3,5-hexatriene (DPH) and anthroyloxy fatty acids, which invade all hydrophobic regions of the cell. Using TMA-DPH, it was shown that mouse malaria parasite Plasmodium berghei induced a statistically highly significant increase (8%) in the plasma membrane fluidity of the host erythrocyte. The physical factors, which might critically influence the measurements in this study, i.e. the fluorescence lifetime of the probe and the contribution of scattered light, were carefully controlled. The effect observed is discussed on the basis of earlier established metabolic changes in the membrane following infection, namely phospholipidic and cytoskeleton modifications.
Biology of the cell / under the auspices of the European Cell Biology Organization, 1988
Blood cells, 1990
The discrimination between erythrocyte and Plasmodium proteases is now made easier by using synth... more The discrimination between erythrocyte and Plasmodium proteases is now made easier by using synthetic fluorogenic substrates, high-pressure liquid chromatography, reliable methods of cell preparation, as well as radiolabeled extracts from in vitro cultures of P. falciparum. The reinvasion process of an erythrocyte by a merozoite involves specific proteinases, which were recently identified using fluorogenic peptidyl-AEC substrates and by analysis of schizont and merozoite extracts with the gelatin-SDS-PAGE method. The biological targets of both host and parasite proteinases are not yet well characterized because Plasmodium-infected red blood cells contain at least four compartments with different pH values, which could modulate the proteinase activities according to their pH range activity. The processing of the precursor for the major merozoite surface antigens involves cleavage of very specific peptidic bonds by, so far unknown, proteinases. The depletion of the erythrocyte cytosk...
Infection and immunity, 1990
[35S]methionine-radiolabeled proteins from the Babesia divergens Rouen 1987 isolate were immunopr... more [35S]methionine-radiolabeled proteins from the Babesia divergens Rouen 1987 isolate were immunoprecipitated with immune sera from three potential hosts: human, ox, and gerbil. The results showed a constant humoral response against major babesial antigens. Similarly, immunoprecipitation of radiolabeled in vitro culture supernatant demonstrated that the exoantigens of 37, 46, 70, and 90 kDA were the immunodominant polypeptides, whatever the host. The effects of vaccination with concentrated supernatant from B. divergens Rouen 1987 in vitro cultures (30 to 40% parasitemia) were examined in gerbils inoculated with the homologous B. divergens isolate. Gerbils having received two or three injections of a whole vaccine dose (1.5 ml of parasitized culture supernatant equivalent [PCSE]) or of a 1:5 diluted vaccine dose (0.3 ml of PCSE) showed 100% survival after intraperitoneal challenge with 10(6) B. divergens-infected gerbil erythrocytes. Moreover, two or three injections of a 1:25 diluted vaccine dose (0.06 ml of PCSE) or 9% NaCl or 1.5 ml of unparasitized culture supernatant equivalent resulted in a mortality rate of 80 to 90% of the infected gerbils. Immunoprecipitation and immunofluorescence assays performed with antisera from vaccinated and control gerbils demonstrated that a single vaccine injection induced a humoral response, which increased slightly after the second or third injection. After challenge, antibody levels increased significantly, although the immunoprecipitation did not display any modification of Babesia antigen patterns.
Infection and immunity, 1991
The immunoprecipitation of [35S]methionine-radiolabelled antigens from different Babesia divergen... more The immunoprecipitation of [35S]methionine-radiolabelled antigens from different Babesia divergens isolates by using bovine, gerbil, and human immune sera has shown that many B. divergens proteins contain epitopes shared between isolates. The cross-protective capacity of culture-derived soluble immunogens from the B. divergens Rouen 1987 isolate was tested against different B. divergens isolates. Results showed complete protection against the 7107b French isolate and substantial protection against the Weybridge 8843 English isolate (80% protection) and the Munich 87 German isolate (60% protection). In order to explain these vaccination results and to assess both the common and variable antigenicity of B. divergens, the antigenic patterns of the challenge isolates (Rouen 1987, 7107b, Weybridge 8843, and Munich 87) were compared by immunoprecipitation, using gerbil antisera raised against the Rouen 1987 vaccine isolate. Differences in the antigenic patterns and in the cross-protection...
Journal of ultrastructure research, 1977
Uploads
Papers by Joseph Schrével