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E Moreau

Publications and source records attributed to E Moreau.

At least 37 records · Page 2Linked to original sources
PubMed1997

Alternative processing of the maize Ac transcript in Arabidopsis.

The successful application of the maize transposable element system Ac/Ds as a genome mutagen in heterologous plant species has recently proved the versatility and power of this technique in plant molecular biology. However, the frequency of Ac/Ds transposition is considerably lower in Arabidopsis thaliana than in most other dicot plant species that have been studied. Since previous research has established that transcripts derived from monocot genes can be alternatively processed in dicot plants, we have investigated both the efficiency of intron splicing and polyadenylation of the maize Ac transposase pre-mRNA in Arabidopsis thaliana, Nicotiana tabacum, Nicotiana plumbaginifolia and Zea mays. In this paper, we demonstrate that intron 4 is alternatively spliced within Arabidopsis, using cryptic 5' and 3'splice sites within the intron sequence, leading to a heterogeneous population of full length of transposase transcript. Furthermore, analysis of transposase transcript polyadenylation revealed that at least four alternative poly(A) sites were utilized between introns 2 and 3, resulting in truncated transposase transcripts. Finally, by Northern blotting, we established that the truncated transposase transcript was the most abundant form of transposase message in Arabidopsis. In contrast to these findings, the alternative splicing and premature polyadenylation of Ac message in Arabidopsis was unparalleled in the other species examined. We suggest that the poor frequency of transposition of Ac in Arabidopsis may be in part due to the low quantity of correctly processed transposase transcript available in this species.

Alternative Splicing↗
PubMed1997

[Diagnosis of bovine fascioliasis using serology of pools of sera. Interpretation in field conditions].

The efficacy of a serological test (ELISA with excretory-secretory products of Fasciola hepatica as an antigen) for the diagnosis of bovine fascioliasis was assessed under field conditions using pools of sera from 170 herds. Blood samples were collected from six to ten heifers and from five to ten adults in each herd. In 92 of the herds (Group 1) the animals had not been treated for fascioliasis; in 78 herds (Group 2), a fasciolicide had been used 3 to 6 months earlier. In each herd, three serum pools were examined: aliquots from all the animals sampled in a herd (GM); aliquots from heifers only (PM); and aliquots from the cows only (PM). Individual sera and the pools (GM and PM) were analyzed similarly and the specific antibody titer was calculated by comparison with laboratory standards. The antibody titer for pooled sera were correlated with the proportion of positive sera in the pool (P < 0.0001); but these could not be used to estimate the prevalence of seropositivity in a herd. Diagnosis based on pooled sera was less effective for the detection of low prevalences of seropositivity in Group 2 than in Group 1 because the antibody titer decreases after fasciolicide treatment. Infection was always detected using pooled sera in herds with a prevalence of seropositivity of more than 60% (GM) in Group 1, or with a prevalence of seropositivity of more than 70% in Group 2. The best method for herd diagnosis of fascioliasis was based on the presence of a positive test in either of the two PM groups. Using this method, all infected herds with a prevalence of seropositivity of more than 30% in Group 1, or 50% in Group 2, were accurately detected.

Animals↗
PubMed1996

Rat metanephric organ culture in terato-embryology.

The development of the permanent mammalian kidney, or metanephros, depends on mesenchymal-epithelial interactions, leading to branching morphogenesis of the ureteric bud that forms the collecting ducts and to conversion of the metanephric mesenchyme into epithelium that forms the nephrons. Rat metanephric organ culture in which these interactions are maintained is a valuable in vitro model system for investigating normal and abnormal renal organogenesis. Methods were designed to evaluate either the capacity of the ureteric bud to branch or that of the mesenchyme to form nephrons. Both are based on specific staining of the ureteric bud and the glomeruli with lectins. Using this approach, we have shown that retinoids are potent stimulating factors of nephrogenesis, acting through an increase in the branching capacity of the ureteric bud. On the other hand, several drugs such as gentamicin and cyclosporin A were found to reduce the number of nephrons formed in vitro. While gentamicin affects the early branching pattern of the ureteric bud, cyclosporin may affect the capacity of the mesenchyme to convert into epithelium. This methodology therefore appears a potentially useful tool for toxicological studies of new drugs.

Animals↗
PubMed1996

Metanephros organogenesis is highly stimulated by vitamin A derivatives in organ culture.

Vitamin A and its metabolic derivatives are known to be key signalling molecules in regulating morphogenetic events in vertebrate development. Here we investigated their possible involvement during mammalian kidney development using paired rat metanephros organ culture. Metanephroi were explanted from 14-day-old embryos and cultured for six days in a chemically defined medium containing a retinoid at a dose of 10(-11) to 10(-4) M. Retinol, all-trans and 9-cis retinoic acid were able to promote metanephros growth and differentiation in vitro. A significant increase in the number of nephrons was observed from 10(-8) M of retinol and 10(-10) M of all-trans retinoic acid, before any change in growth parameters. A threefold increase in the number of nephrons was obtained at a dose of 10(-6) M. At low retinoid concentrations, there was a modulating effect of triiodothyronine on retinoid-stimulated nephrogenesis since the absence of triiodothyronine in the medium enhanced the nephrogenic stimulation. Exposure of metanephroi from 13-day-old embryos to all-trans retinoic acid (10(-7) M) led to a sixfold increase of nephron formation. Finally, we analyzed the branching pattern of the ureteric bud and showed that within 48 hours of culture, it was significantly more developed upon retinoid exposure. In conclusion, this study demonstrates that retinoic acid is a key regulator of renal organogenesis in controlling nephrogenic induction processes and ureteric bud patterning, and that the younger the metanephros, the greater the effect.

Animals↗
PubMed1996

Early defect in branching morphogenesis of the ureteric bud in induced nephron deficit.

Development of the metanephric kidney during embryogenesis can be altered both in vivo and in vitro by exposure to gentamicin, which may lead to oligonephronia. To study the role of the ureteric bud in nephron deficit genesis, we used metanephros organ cultures exposed to gentamicin as a model of impaired nephrogenesis. Ultrastructural localization of the antibiotic showed that by eight hours it was already present within the epithelial cells of the ureteric bud and in its growing ends, and also trapped in the adjacent blastema. Using confocal microscopy and image analysis, we devised a quantitative approach to analyze the branching pattern of the ureteric bud, and showed that by 24 hours of culture, despite no change of explants growth, gentamicin had significantly decreased the number of branching points. This effect involved the early branching events and was limited to end buds that had no nephron anlagen nearby. Our findings indicate that impaired branching morphogenesis of the ureteric bud is the likely event of gentamicin-induced nephron deficit.

Animals↗
PubMed1996

Interference of soluble TNF-alpha receptors in immunological detection of tumor necrosis factor-alpha.

We have studied the interference of soluble tumor necrosis factor-alpha receptor p55 (sTNF-R55) on the quantification of tumor necrosis factor-alpha (TNF-alpha) in three immunoassays: the commercially available enzyme amplified-sensitivity immunoassay (EASIA) of Medgenix and the ELISA of Boehringer Mannheim, and an assay based on electrochemiluminescence (ECL) technology. TNF-alpha measurements by EASIA and ELISA were not affected by the presence of sTNF-R55, but results by the ECL method were clearly influenced by the receptor. We then performed a second set of experiments with the ECL system to examine what factors might influence the importance of interference from sTNF-R55 and soluble TNF-alpha receptor p75 (sTNF-R75), which influences TNF-alpha measurements the same as sTNF-R55. We found that extending the incubation time and increasing the concentration of capture antibody decreased the interfering capacity of sTNF-R55 and sTNF-R75. A clear insight into these phenomena is of utmost importance for correct interpretation of cytokine quantification.

Enzyme-Linked Immunosorbent Assay↗
PubMed1996

[Unusual spinal and pulmonary metastases].

We present the clinical and imaging findings of a 72 year old man with lytic dorsal bone lesions and a pulmonary spread of nodules (miliary) that were mistakenly attributed to a cancerous disease.

Aged↗
PubMed1994

Performance of the Coulter STKS and the Sysmex NE-1500 in a paediatric population.

The Coulter STKS and the Sysmex NE-1500 were evaluated for their performance in paediatric samples. Special attention was paid to the ability of both instruments to detect white blood cell morphology abnormalities. Therefore a population with a high frequency of pathologies was selected. The studied population included children aged between 1 month and 14 years, 45% of which suffered from oncological and/or haematological diseases. Two hundred and forty blood samples were analysed. The leukocyte differentiation results from the Coulter STKS and the Sysmex NE-1500 were compared with the manual microscopic method. The differentials compared very well for neutrophils, lymphocytes and eosinophils. Sensitivity and specificity for the detection of blasts, immature granulocytes, left shift and atypical lymphocytes were examined. While specific morphology flagging showed a rather low sensitivity, blasts and immature granulocytes were mostly detected by the two systems, taking into account white blood cell alarm flags other than the two mentioned above. The overall sensitivity for the detection of white blood cell abnormalities was better with the Coulter STKS, whereas the Sysmex NE-1500 showed a higher specificity. In an ancillary study which was performed exclusively on neonatal samples, of which 80% originated from preterm infants, we found a limited sensitivity for the detection of low percentages of nucleated red blood cells for both analysers. The high frequency of abnormalities, together with the limited sensitivity mentioned above, prompted us to review all neonatal samples in the future.

Adolescent↗
PubMed1994

Defect of nephrogenesis induced by gentamicin in rat metanephric organ culture.

BACKGROUND: In the rat, in utero exposure to gentamicin during early renal differentiation leads to a permanent nephron deficit. The aim of the present study was to analyze, in vitro, the potential direct effect of gentamicin on early nephrogenesis. EXPERIMENTAL DESIGN: We used paired rat metanephric organ cultures from 14 (F14) or 15-day-old (F15) fetuses. We measured gentamicin accumulation into explanted metanephroi and then assessed in vitro growth in the absence or presence of the drug. Glomerular labeling and counting were performed on the whole explant to analyze the effect of antibiotics on early nephrogenesis. RESULTS: Growth of F14 metanephric explants in the presence of 50 micrograms of gentamicin/ml was significantly reduced from 4 days onwards as compared to controls, whereas F15 explants grown with gentamicin displayed a normal in vitro development. After 6 days of culture, F14 and F15 explants had the same accumulation of gentamicin (1 microgram/mg protein) but the gentamicin content was 4 times larger in F15 explants. At both ages, gentamicin-exposed metanephric explants exhibited a significant reduction in their number of nephrons. However, the effects of 50 micrograms of gentamicin/ml on nephrogenesis were significantly more drastic on F14 than F15 explants (35% versus 18%). When grown with 0.5 microgram of gentamicin/ml, F14 explants still exhibited a 16% defect in nephrogenesis as compared with controls, and about the same reduction was observed for cultures in the presence of 100 micrograms/ml of streptomycin and 100 IU/ml of penicillin. Incubation of F14 explants with streptomycin alone for 6 days had no effect on nephrogenesis. CONCLUSIONS: These results indicate that gentamicin induces a significant reduction in the number of nephrons in metanephric explants and that this effect is more important on less differentiated metanephroi. Metanephric organ culture combined with glomerular labeling represents a useful model to test the effect of various growth factors and other drugs on early nephrogenesis.

Animals↗
PubMed1993

Neurotoxin binding and allosteric modulation at receptor sites 2 and 5 on purified and reconstituted rat brain sodium channels.

Purified and reconstituted sodium channels have previously been shown to be functional in voltage-dependent ion conductance and in high affinity binding of tetrodotoxin and saxitoxin at neurotoxin receptor site 1 and alpha-scorpion toxins at receptor site 3, but high affinity binding of neurotoxins at receptor sites 2, 4, and 5 has not been demonstrated. The pyrethroid insecticide RU39568 enhances the specific binding of [3H]batrachotoxinin A 20-alpha-benzoate (BTX-B) to neurotoxin receptor site 2 on purified and reconstituted sodium channels up to 500-fold, reducing the Kd to 1.5 nM. Brevetoxins and alpha-scorpion toxins cause further allosteric enhancement of BTX-B binding. The pyrethroids deltamethrin and bifenthrin and the nonpyrethroid insecticide 2,2-bis(p-chlorophenyl)trichloroethane can partially substitute for RU39568 in enhancing BTX-B binding, but other pyrethroids are inactive. The brevetoxin PbTx-1 binds specifically to neurotoxin receptor site 5 on purified and reconstituted sodium channels with a Kd value of approximately 30 nM. Brevetoxin binding is enhanced up to 2-fold by the combination of batrachotoxin and RU39568. The allosteric enhancement of BTX-B binding by RU39568 is voltage dependent, decreasing progressively with depolarization to 0 mV. In contrast, PbTx-1 binding is not voltage dependent and PbTx-1 reduces the voltage dependence of the effect of RU39568. The results demonstrate restoration of high affinity binding and allosteric interactions of ligands at neurotoxin receptor sites 2 and 5 on purified and reconstituted sodium channels and provide an experimental approach to covalent labeling and identification of the peptide components of those receptor sites.

Allosteric Regulation↗
PubMed1992

Effects of an early weaning on phosphate transport maturation in the rat kidney: influence of the phosphate content of the diet.

The renal phosphate (Pi) transport system matures during the 3rd postnatal wk in the rat by an increase in the carrier affinity for sodium-cotransported phosphate. This study examines the ability of pups to adapt their renal Pi transport to the dietary phosphorus content during this period of carrier affinity maturation, corresponding to the weaning period in the rat. Clearance experiments and brush border membrane studies were performed on 21-d-old rats weaned early on d 16 onto a low phosphate diet (LPD, 0.19 g/100 g), a normal phosphate diet (control, 0.78 g/100 g), or a high phosphate diet (HPD, 1.5 g/100 g). In LPD rats, the Pi fractional excretion (0.3 +/- 0.1%) was lower than in controls (18 +/- 3%, p < 0.001). It remained very low (0.21 +/- 0.05% in LPD rats versus 40.5 +/- 6.3% in controls, p < 0.001) after Pi perfusion (1.5 mumol.min-1.100 g-1) and the reabsorbed Pi per min, corrected for the glomerular filtration rate, was higher than in the two other groups. The calcium fractional excretion (12.6 +/- 1.02%) in the LPD rats was much higher than in the controls (0.42 +/- 0.2%, p < 0.001). In contrast, HPD rats had an elevated Pi fractional excretion (41 +/- 4%, p < 0.001), whereas reabsorbed phosphate per min corrected for the glomerular filtration rate was not increased by a Pi load.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1991

Rapid control of purity for the cytoplasm of male-sterile seed stocks by means of a dot hybridization assay.

To produce hybrids, one member of the parental line is genetically made male-sterile. This male-sterile trait is encoded by mitochondria so that it is maternally inherited. Consequently, the progeny of a male-sterile plant is fully sterile. Nevertheless, during the handling of cytoplasmic male-sterile seed stocks, some mixture with seeds of the maintainer lines can occur. Up to the present time, the only way to check the homogeneity of the cytoplasmic male-sterile seed stock was to grow the plants until flowering time. We have developed a method which can be used immediately after the harvest, allowing us to check samples from both sunflower and sugar beet. We used the mitochondrial plasmid, present only in the maintainer lines, as a probe for the total nucleic acids prepared from the cytoplasmic male-sterile seed stocks which might be contaminated. The signals compared to those of samples artificially contaminated allow us to measure as few as one male-fertile seed in 1000 seeds in a rapid and accurate manner.

Blotting, Northern↗
PubMed1989

Development of acid secretory function in the rat stomach: sensitivity to secretagogues and corticosterone.

Gastric acid secretion was studied in anesthetized rats from day 6 of the postnatal period up to the time of weaning. Basal H+ secretion was detected from day 6 in the first group studied (2.4 +/- 0.2 muEq of H+/10 min/100 g of body weight, BW) and remained constant up to the time of weaning (day 18: 2.5 +/- 0.2 muEq of H+/10 min/100 g of body weight) except for the period between days 10 and 12, when it fell significantly (1.5 +/- 0.06 muEq H+/10 min/100 g of BW on day 12). Both histamine H2 receptor sensitivity and intracellular transduction mechanism activities were evaluated by studying the secretory responses to histamine, impromidine (an H2 receptor agonist), cimetidine (an H2 receptor antagonist), forskolin (a direct adenylate cyclase activator), and dibutyryl (db) cAMP (an analogue of cAMP, the intracellular messenger mediating the response to histamine). The effects of pentagastrin and carbachol were also determined. The secretory responses obtained on days 6, 8, and 18 were similar and represented about threefold increases over basal secretion for all the secretagogues used. After weaning on day 20, both the basal secretion and the response to secretagogues were significantly increased compared with those of unweaned animals. On day 12, the responses were always weaker than on both days 8 and 18. Injection of 1 mg/kg of corticosterone 21 acetate daily from day 8 resulted on day 12 in a basal secretion and a response to histamine equivalent to those measured in 18-day-old pups not injected.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Development of sodium and chloride transport across fetal and newborn rat stomach in vitro.

1. Unidirectional and net Na+ and Cl- fluxes were determined across isolated fetal rat stomach 19-21 days post-coitum, and across the stomach of newborn rats aged 5 or 12 days. 2. On fetal day 19, absorption of both Na+ and Cl- was greater than the short-circuit current, Isc (net Na+ flux, JnetNa = 4.7 +/- 1.0 and net Cl- flux, JnetCl = 5.4 +/- 1.4 mu equiv cm-2 h-1 vs. Isc = 0.9 +/- 0.1 mu equiv cm-2 h-1). Mucosal addition of 10 microM-amiloride did not significantly alter JnetNa, JnetCl, Isc or total conductance. 3. However, on fetal day 20, neutral absorption of NaCl was no longer observed but amiloride had inhibited electrogenic absorption of Na+, and significant active secretion of Cl- was observed (JnetCl = -1.3 +/- 0.6 mu equiv cm-2 h-1). On day 21 (i.e. 24 h before birth), values for JnetNa, JnetCl, and Isc were not different from those determined on adult gastric mucosa. 4. After birth, NaCl transport continued to exhibit its prenatal characteristics on day 5 but not on day 12, when Na+ and Cl- were both absorbed; on that day, JnetNa-Isc was equal to both JnetCl and to the amiloride-insensitive component of Isc, indicating that neutral NaCl absorption had resumed. 5. These data show that in rat stomach, NaCl transport differentiates on fetal day 20, when H+ secretion is first observed, and thereafter undergoes biphasic development. 6. The significant Cl- absorption observed on post-natal day 12 was concomitant with the inhibition of net H+ secretion.

Amiloride↗
PubMed1987

Ontogeny of rat gastric H+-K+-ATPase activity.

Gastric H+-K+-ATPase activity was examined in subcellular fractions (P1, 1,000 g; P2, 20,000 g; P3, 100,000 g) obtained from fundic mucosae of fetal, newborn, and adult rats. Depending on the tissue secretory state the distribution of this enzyme activity predominates in P3, i.e., resting adult, or in P2, i.e., stimulated adult, while total enzyme activity (P2 + P3) remains constant. Enzyme activity was detected as soon as day 19 of gestation and P2 + P3 reached 2.2 +/- 0.2 mumol Pi X mg prot-1 X h-1 at parturition. H+-K+-ATPase activity steadily decreased from 4.0 +/- 0.7 mumol Pi X mg prot-1 X h-1 on day 6 after birth to approximately 0 on day 12. This activity recovered as soon as day 13 (3.5 +/- 0.6 mumol Pi X mg prot-1 X h-1) and continued to rise slowly until adulthood. Incubation of subcellular fractions with 0.1 mM omeprazole resulted in a total loss of H+-K+-ATPase activity at all the stages of development examined. These studies of functional relationship during the development between gastric acid secretion and distribution of gastric H+-K+-ATPase activity among P2 and P3 fractions indicate that this last could be considered as an index of the secretory state of the parietal cell. This enzyme's pattern of development in P2 + P3, correlated with the one previously observed for stimulated H+ secretion in intact tissue, suggest that the H+-K+-ATPase is the limiting step in response to secretagogues during postnatal period.

Adenosine Triphosphatases↗