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J P Morin

Publications and source records attributed to J P Morin.

At least 19 recordsLinked to original sources
PubMed2000

Role of solid-phase microextraction in the identification of highly volatile pheromones of two Rhinoceros beetles Scapanes australis and Strategus aloeus (Coleoptera, Scarabaeidae, Dynastinae).

Solid-phase microextraction (SPME) samplings from live insects or natural secretion allowed one to identify the aggregation pheromones of the pest beetles Scapanes australis and Strategus aloeus by efficient and rapid isolation of their highly volatile (72 < M(r) < 116) components. S. australis male pheromone was identified as a 84:12:4 (w/w) mixture of 2-butanol [67:33 (R)-(-):(S)-(+) ratio], 3-hydroxy-2-butanone and 2,3-butanediol [43:17:40 (R,R)-(-):(S,S)-(+):meso ratio], and S. aloeus pheromone as a 95.5:4.0:0.5 (w/w) mixture of 2-butanone, 3-pentanone and sec.-butyl acetate by GC-MS using conventional and chiral capillary columns. This is the first report of Scarabaeidae pheromones based on such small and common molecules.

Animals↗
PubMed2000

Toxicity of diesel engine exhausts in an in vitro model of lung slices in biphasic organotypic culture: induction of a proinflammatory and apoptotic response.

Precision-cut rat lung slices in organotypic culture placed in a biphasic air/liquid system were used for this study. This model allowed pathological as well as cellular and molecular biology investigations to be carried out. Slices were exposed to a continuous flow of diluted diesel exhaust, with a pO2 adjusted to 20% to avoid hypoxia-induced effects. The exposure system allowed five exhaust concentrations from the same diesel engine to be studied concomitantly, and also allowed the impact of removing the particulate matter using a filter cap on the exposure vials to be evaluated. Lung slices were exposed for 3 or 6 h to whole or filtered diesel exhaust. DNA integrity was characterized by two different techniques: (1) an ELISA for the determination of nucleosomes, and (2) the histochemical TUNEL method. By the TUNEL method, apoptotic cells were detected after a 6-h exposure followed by an incubation period of 18 h in a controlled atmosphere comprising 5% CO2/95% O2. Under these conditions, apoptotic nuclei were more frequent in slices exposed to diesel exhaust than in control slices. Cytokine production (tumor necrosis factor alpha, interleukin-1beta) in the culture medium was measured using an ELISA technique. After a 3-h exposure only TNF-alpha was detected and increased in the culture medium of lung slices exposed to diesel exhaust. Under the same conditions, nucleosome levels in the slices increases in a dose-dependent way. In conclusion, whole diesel exhaust induced an inflammatory response and DNA alterations which were reduced by filtration, thus indicating the important role of the particulate matter in diesel exhaust.

Animals↗
PubMed2000

The genetics of phenotypic plasticity. IX. Genetic architecture, temperature, and sex differences in Drosophila melanogaster.

We examined the genetic architecture of plasticity of thorax and wing length in response to temperature in Drosophila melanogaster. Reaction norms as a function of growth temperature were analyzed in 20 isofemale lines in a natural population collected from Grande Ferrade near Bordeaux (southern France) in two different years. We found evidence for a complex genetic architecture underlying the reaction norms and differences between males and females. Reaction norms were negative quadratics. Genetic correlations were moderately high between traits within environments. Among characteristic values, the magnitudes of genetic correlations varied among traits and sexes. We hypothesized that genetic correlations among environments would decrease as temperatures became more different. This expectation was upheld for only one trait, female thorax length. For males for both traits, the correlations were large for both very similar and very different temperatures. These correlations may constrain the evolution of the shape of the reaction norms. Whether the extent of independence implies specific regulatory genes or only a specific allelic regulation of trait genes can not be decided from our results.

Animals↗
PubMed1999

Acrolein toxicity: comparative in vitro study with lung slices and pneumocytes type II cell line from rats.

Toxicological effects of acrolein have been studied in precision-cut rat lung slices and in L2 cells, a rat pneumocyte II cell line. These two models were cultured for 24 h with or without acrolein (0-100 microM in L2 cells; 0-200 microM in lung slices). Treatment with this pneumotoxicant produced a concentration dependent decrease in intracellular ATP levels. Acrolein concentrations higher than 50 microM induced ATP decrease in slices, while this decrease occurred from 10 microM acrolein in L2 cells. Detoxification marker evaluations showed that mostly the glutathione pathway was altered after acrolein treatment in both models. Intracellular glutathione (GSH) levels were drastically increased with an acrolein concentration of 10 microM. This increase was concomitant with glutathione-S-transferase (GST) and glutathione reductase (GRED) activities in L2 cells. After this strong increase, these enzymatic activities as well as GSH levels were quickly decreased. In precision-cut rat lung slices, the induction of the glutathione pathway was less clear-cut. A bell-shaped dose response curve was observed with a maximum for 5 microM acrolein for GST and GRED activities. These differences between acrolein toxic ranges could be explained by the presence of an active detoxification pathway in slices compared to its relative lack in L2 cells.

Acrolein↗
PubMed1999

Development of a new in vitro system for continuous in vitro exposure of lung tissue to complex atmospheres: application to diesel exhaust toxicology.

The purpose of this study was the development of a new incubation system that can allow continuous exposure of lung tissue to complex atmospheres as a tool for the assessment of aerial environmental lung toxicology. To assess the pertinence of this new exposure system, we studied the impact of diesel engine exhausts as a complex atmosphere containing both gaseous and particulate fractions and have been able to discriminate between the toxicological impacts of the gaseous phase and particulate matter from diesel exhausts. Continuous flow-through rotating chambers with controlled PO2, pCO2, and hygrometry have been designed in which lung slices are positioned in rolling inserts that allow free access of atmosphere to the exposed lung tissue. Under control conditions, cell viability was preserved for at least 48 h as assessed by intracellular ATP, GSH, and K+ levels and slice O2 consumption levels. Short-term exposure (1 h) to diesel whole exhausts did not affect intracellular potassium or slice O2 consumption, while intracellular ATP and GSH levels were markedly decreased. Exposure to filtered exhausts showed less marked effects on both ATP and GSH levels. Superoxide dismutase activity was decreased in a similar way by both total and filtered exhausts while Se(+)-dependent glutathione peroxidase activity was induced by filtered exhausts to a larger extent than after total exhaust exposure, showing different response patterns of lung tissue after exposure to whole or filtered exhausts. In conclusion, this newly designed model opens a promising area in in vitro environmental lung toxicology testing.

Adenosine Triphosphate↗
PubMed1997

Morphological and biochemical characterization of primary culture of rabbit proximal kidney tubule cells grown on collagen-IV coated Millicell-CM.

The aim of this study was to better characterize rabbit proximal kidney tubule cells cultured on collagen IV-coated porous inserts, as compared to the same cells seeded in standard plastic wells. Total protein contents in confluent monolayers on permeable membranes were about twofold higher than those measured in confluent cultures in plastic wells. Microscopy examinations suggested that such a difference was probably due to a higher cell density and to an impressive development of the apical brush-border membrane. Moreover, measurement of unidirectional transport of p-aminohippuric acid and tetraethylammonium bromide confirmed the high polarization level of cultures on porous inserts. Results of methyl(alpha-D-[U-14C]glyco)pyranoside uptake suggested that cell phenotype was probably influenced by culture conditions. Analysis of different markers as a function of time in culture showed decreases of alkaline phosphatase (AP), gamma-glutamyltranspeptidase (GGT), and Na(+)-K(+)-ATPase activities as well as increases in LDH, ATP, and glutathione levels, similar to those formerly reported for cells cultured in standard plastic plates. However, comparative data from 6-d-old monolayers have shown that AP, GGT, Na(+)-K(+)-ATPase, glutathione reductase (GRED), and selenium-dependent glutathione peroxidase (Se-GPX) activities were 2.8-, 2.6-, 1.6-, 1.2-, and 2.1-fold, respectively, better preserved on precoated permeable membranes. On the other hand, this paper reports for the first time in the literature that GRED and SE-GPX, two phase II detoxification enzymes, were well maintained in cultures of rabbit proximal kidney tubule cells. Our results show that culturing rabbit proximal kidney tubule cells on collagen IV-coated porous membranes was accompanied by an improvement of both morphological and biochemical properties of the cells.

Adenosine Triphosphate↗
PubMed1997

Cell lines with extended in vitro growth potential from human renal proximal tubule: characterization, response to inducers, and comparison with established cell lines.

Few model systems exist for the study of injury to human renal proximal tubule epithelium. Optimized differentiated human renal epithelial cell lines with extended in vitro growth potential would provide an alternative model system to primary culture or other available non-human mammalian kidney cell lines. For this purpose, human renal tubule epithelial cells were isolated from normal kidney cortex and exposed in culture to a hybrid immortalizing virus, adenovirus 12-SV40. Cell lines were developed by limiting dilution, and three selected cell lines were screened for growth pattern, production of immortalizing virus, tumorigenicity, and ploidy. Cell lines were also monitored for response to inducer agents and matrix factors and were screened for expression of biochemical properties and differentiation markers of renal epithelium. All three are nonproducers of the immortalizing virus and are nontumorigenic. They grow in monolayer, have intermediate growth kinetics, and express markers of renal proximal tubular epithelium by immunohistochemistry. They also express biochemical properties comparable to other widely used proximal tubular cell lines including LLC-RK1, OK, and HK-2 and comparable to human tubular cells in stable culture. Growth medium containing low levels of fetal calf serum, or epidermal growth factor combined with parathyroid hormone, produced optimal growth characteristics, brush border enzyme expression, biochemical properties, and glucose transport in a selected cell line. The addition of dimethyl sulfoxide allows maintenance in morphologically intact monolayers for prolonged periods. These cell lines should be useful model systems for the study of human renal proximal tubular injury or disease.

Adenosine Triphosphate↗
PubMed1997

Evolutionary changes of nonlinear reaction norms according to thermal adaptation: a comparison of two Drosophila species.

While the adaptive significance of discontinuous reaction norms is generally accepted, the evolutionary interpretation of continuous response curves remains speculative, and the occurrence of internal constraints is often suggested as an explanation of experimental observations. In Drosophila melanogaster, various morphometrical traits exhibit convex reaction norms to growth temperature, with a maximum value within the developmental thermal range. We compared a cold-adapted species (D. subobscura) with a mid thermal range at 16 degrees C, to the warm-adapted D. melanogaster (mid thermal range at 22 degrees C) for three different morphometrical traits: wing and thorax length in both sexes and ovariole number in females. Maximum value temperatures were ordered in the same way for the three traits in both species: ovariole number > thorax length > wing length. Significant differences were also observed between the two species for the curvature parameter of the quadratic adjustment. The major observation was a significant lateral shift in the reaction norms: maximum values were observed at much lower temperatures in the cold-adapted species than in the warm-adapted one. The parallelism between mid thermal range variation and the position of the maximum value strongly suggests an adaptive displacement of the response curves. Natural selection may thus act not only on trait mean values but also on phenotypic plasticity and on the shape of reaction norms.

Animals↗
PubMed1996

Comparative impact of cephaloridine on glutathione and related enzymes in LLC-PK1, LLC-RK1, and primary cultures of rat and rabbit proximal tubule cells.

Among kidney tubular epithelial cell types, proximal tubule cells are one of the major renal targets for xenobiotics. Several in vitro culture models have been proposed for use of proximal tubule cells for in vitro pharmacotoxicology studies. This paper reports a comparative study of the response to cephaloridine exposure of two established cell lines from pig (LLC-PK1) and rabbit (LLC-RK1) kidneys and primary cultures of rat and rabbit proximal tubule cells. These cultured cells were first compared for their levels of activity of alpha-methylglucopyranoside transport, alkaline phosphatase, succinate dehydrogenase, and NADPH cytochrome c reductase, their glutathione-dependent activity levels, and their adenylate cyclase response pattern to stimulation by PTH and AVP. The results presented show major phenotypic differences between these four cellular models. The differences observed in glutathione-dependent mechanism activities and regulation may in part be responsible for the variability of the responses of these four cellular models when exposed to cephaloridine.

Animals↗
PubMed1996

The cellular toxicity of two antitumoural agents derived from platinum, cisplatinum versus oxaliplatinum, on cultures of tubular proximal cells.

There is a large scope for the use for cisplatin and its derivatives in the treatment of human malignancies. Nephrotoxicity is their most important use-limiting factor. The aim of this study has been to compare cisplatin (CDDP) and oxaliplatin (1-OHP), a new derivative, on cultures of tubular proximal cells. Three cells models were used: primary culture of rabbit kidney, proximal tubular cells (RPTC) and established opossum kidney (OK) and pig kidney (LLC-PK1) epithelial cell lines. Results indicate that in these three culture systems, the cytotoxicity-ranking of the two molecules were in agreement with their in vivo nephrotoxicity (CDDP > 1-OHP), but were less cytotoxic for OK and LLC-PK1 cells than for RPTC. Functional and biochemical evaluations in RPTC indicate that toxic effects of platinum derivates are exerted on DNA, protein synthesis and glucose uptake. 1-OHP effect on DNA synthesis seems to be more effective, but induced a more progressive cytotoxicity. Alteration of glutathione-dependent detoxication activities may reflect the occurrence of a lipid peroxidation process. The present study showed that 1) RPTC are more suitable that LLC-PK1 or OK cells for investigating the nephrotoxicity of platinum derivatives; 2) 1-OHP seems to have a more powerful pharmacological effect than CDDP. The toxic effect ratio seems to promise greater safety with 1-OHP than with CDDP.

Animals↗
PubMed1996

[Ethyl 4-methyloctanoate, major component of male pherome in Oryctes rhinoceros (L.) (Coleoptera, Dynastidae)].

Ethyl 4-methyloctanoate, which has already been described in Oryctes monoceros, has been identified, using extracts of effluvia collected from males, as being a major component of the male pheromone of O. rhinoceros. Field trials have been carried out in North Sumatra, Indonesia. Ethyl 4-methyloctanoate synthesized in the laboratory and released at 10 mg/d resulted in the capture of 6.8 insects per week per trap, whereas ethyl chrysanthemate (40 mg/d), an allelochemical compound once used as an attractant, only led to the capture of 0.3 insects, and the control none at all. The insects captured with the pheromone were 81% females, the majority being sexually mature. Discovery of this compound opens up new prospects for O. rhinoceros control.

Animals↗
PubMed1995

Expression and subcellular distribution of phosphoenolpyruvate carboxykinase in primary cultures of rabbit kidney proximal tubule cells: comparative study with renal and hepatic PEPCK in vivo.

The behaviour of the phosphoenolpyruvate carboxykinase (PEPCK) in rabbit proximal tubule cells in primary culture was investigated and compared with renal and hepatic PEPCK in vivo. The enzyme activity decreased rapidly in rabbit proximal tubule cells developed in hormonally defined medium supplemented with glucose and insulin. In this condition, the cytosolic form disappears with time. Without glucose and insulin, the subcellular location of PEPCK is similar to the location observed in proximal tubule freshly isolated and in renal cortex, with approx. 50% of mitochondrial form and approx. 50% of cytosolic form. However, the levels of mRNA that encode the cytosolic PEPCK are not detectable in cell cultures, whatever the medium composition. Treatment with dibutyryl cAMP caused a 14-fold induction of PEPCK mRNA in 6 h. This result indicates that the transcription of cytosolic PEPCK can be induced in cell cultures. Lactate or pyruvate additions did not modify the levels of PEPCK mRNA whereas specific activity increased rapidly, suggesting an activation of an inactive form in cell cultures. Moreover, lactate induced increased specific activity of the sole mitochondrial form while pyruvate induced increased specific activities of both mitochondrial and cytosolic form. Thus, subcellular location of PEPCK in rabbit proximal tubule cells appears to be modulated by the available substrate in culture medium. This observation parallels the changes observed in vivo since a modification of subcellular location of this enzyme was seen between fed and fasted rabbit, when subcellular distribution remains similar between fed and starved rats. Moreover, in the fasted liver of rabbit, a decrease of the mitochondrial PEPCK specific activity is seen concomitant with an increase in cytosolic PEPCK activity. These results point out the relative contributions of the cytosolic and mitochondrial PEPCK to rabbit gluconeogenesis.

Animals↗
PubMed1995

Impact of cephaloridine on glutathione and related enzymes: comparison of in vivo and in vitro rat models.

The aim of this study was to investigate the early effects of cephaloridine (CPH) on glutathione-dependent phase II detoxification in the rat proximal tubular cell and to find an in vitro alternative to the in vivo model. The in vivo study was conducted in three groups of rats which received CPH at doses of 250, 500 or 750 mg/kg per day for 3 days, while another group received 500 mg/kg as a single dose. For the in vitro study, rat renal proximal tubular cultured cells were exposed to CPH at concentrations of 0.3, 0.6, 1, 1.7 mM for 24, 48 and 72 h. Glutathione-dependent detoxification was evaluated in vivo and in vitro on the basis of total intracellular glutathione (GSH), glutathione S-transferase (GST) and glutathione peroxidase (GPX). Glutathione reductase (GRED) and GST mRNA levels were also determined. Results of in vivo and in vitro models were comparable in terms of the early increase of GSH, GST and GRED. This increase had a bell-shaped dose-response with a maximum at 500 mg/kg in vivo and 1 mM in vitro. Beyond these doses, GSH and its dependent enzyme levels decreased, associated with cytotoxicity in vitro and renal insufficiency in vivo. The increased GST activity was associated with an increased level of GST7 in vivo and a markedly increased level of GST1-2 in vitro. We concluded that the in vitro model can be used as an alternative to animal experimentation to study glutathione-dependent detoxication. Low cytotoxic doses of CPH induced an early increase of glutathione phase II-dependent detoxification enzymes.

Animals↗
PubMed1995

Polarity and transport properties of rabbit kidney proximal tubule cells on collagen IV-coated porous membranes.

A high degree of functional polarity has been obtained in primary cultures of rabbit kidney proximal tubule cells grown on collagen IV-coated porous membranes. Tight confluency was attained 6 days after seeding and maintained for at least 6 more days, as shown by analysis of paracellular inulin diffusion. From day 6 onward, L-lactate, ammonia, and D-glucose concentration gradient and a pH difference of approximately 1 unit developed between the two nutrient medium compartments. Confluent monolayers expressed organic ion transport properties higher than those formerly reported for other cell models. Transcellular transport of 20 microM tetraethylammonium was directed from basal to apical compartment and was specifically inhibited by mepiperphenidol (1 mM). Unidirectional transport of 2.4 microM p-aminohippurate also occurred from basal to apical compartment, was saturable, and specifically inhibited by probenecid (1 mM). These results suggest that rabbit kidney proximal tubule cells, cultured under the experimental conditions described here, may be a useful model for the in vitro study of highly polarized renal transport processes.

Ammonia↗