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Biomedical subjects

M P Dubois

Publications and source records attributed to M P Dubois.

At least 19 recordsLinked to original sources
PubMed2001

Identification and characterization of novel organophosphate detoxifying esterase alleles in the Guangzhou area of China.

In the mosquito Culex pipiens, various alleles at the Ester locus provide insecticide resistance. These resistance alleles display a heterogeneous geographical distribution, particularly in China, where they are highly diverse. A new resistance allele, Ester9, coding for the overproduced esterases A9 and B9, is characterized and compared to the known resistant allele Ester8 isolated from the same southern China sample (from Guangzhou). Both alleles provide low but significant resistance to chlorpyrifos (relative synergism ratio [RSR] > 3) and temephos (RSR = 1.4), which is consistent with the low level of gene amplification they display (15 copies for Ester9 and 4 copies for Ester8). The full genomic sequence of the allele coding A8 and A9 is presented, which allowed us to set up a polymerase chain reaction assay to specifically identify these alleles. The peculiar situation in southern China, where numerous resistance alleles coexist, is discussed in comparison with the Mediterranean situation, the only one with a similar diversity of overproduced esterases.

Alleles↗
PubMed1998

Variation of microsatellite size homoplasy across electromorphs, loci, and populations in three invertebrate species.

Size homoplasy was analyzed at microsatellite loci by sequencing electromorphs, that is, variants of the same size (base pairs). This study was conducted using five interrupted and/or compound loci in three invertebrate species, the honey bee Apis mellifera, the bumble bee Bombus terrestris, and the freshwater snail Bulinus truncatus. The 15 electromorphs sequenced turned out to hide 31 alleles (i.e., variants identical in sequence). Variation in the amount of size homoplasy was detected among electromorphs and loci. From one to seven alleles were detected per electromorph, and one locus did not show any size homoplasy in both bee species. The amount of size homoplasy was related to the sequencing effort, since the number of alleles was correlated with the number of copies of electromorphs sequenced, but also with the molecular structure of the core sequence at each locus. Size homoplasy within populations was detected only three times, meaning that size homoplasy was detected mostly among populations. We analyzed population structure, estimating Fst and a genetic distance, based on either electromorphs or alleles. Whereas little difference was found in A. mellifera, uncovering size homoplasy led to a more marked population structure in B. terrestris and B. truncatus. We also showed in A. mellifera that the detection of size homoplasy may alter phylogenetic reconstructions.

Alleles↗
PubMed1998

The acetylcholinesterase gene Ace: a diagnostic marker for the Pipiens and Quinquefasciatus forms of the Culex pipiens complex.

The taxonomy of the Culex pipiens complex remains a controversial issue in mosquito systematics. Based on morphologic characters, 2 allopatric taxa are recognized, namely Cx. pipiens (including the form "molestus") in temperate areas and Cx. quinquefasciatus in tropical areas. Here we report on variability at the nucleotide level of an acetylcholinesterase gene in several strains and natural populations of this species complex. Few polymorphisms were found in coding regions within a subspecies but many polymorphisms were observed between subspecies in noncoding regions. We describe a method based on a restriction enzyme polymorphism in polymerase chain reaction-amplified DNA, in which the presence or absence of one restriction site discriminates Cx. pipiens, Cx. quinquefasciatus, and their hybrids. This technique reliably discriminates mosquitoes from more than 30 worldwide strains or populations. Polymerase chain reaction amplification of specific alleles may also be a useful tool for characterizing specific alleles of each sibling taxon.

Acetylcholinesterase↗
PubMed1994

Molecular characterization of races and vegetative compatibility groups in Fusarium oxysporum f. sp. vasinfectum.

Restriction fragment length polymorphism (RFLP) and vegetative compatibility analyses were undertaken to assess genetic relationships among 52 isolates of Fusarium oxysporum f. sp. vasinfectum of worldwide origin and representing race A, 3, or 4 on cotton plants. Ten distinct vegetative compatibility groups (VCGs) were obtained, and isolates belonging to distinct races were never in the same VCG. Race A isolates were separated into eight VCGs, whereas isolates of race 3 were classified into a single VCG (0113), as were those of race 4 (0114). Ribosomal and mitochondrial DNA (rDNA and mtDNA) RFLPs separated four rDNA haplotypes and seven mtDNA haplotypes. Race A isolates displayed the most polymorphism, with three rDNA haplotypes and four mtDNA haplotypes; race 4 isolates formed a single rDNA group but exhibited three mtDNA haplotypes, while race 3 isolates had unique rDNA and mtDNA haplotypes. Two mtDNA molecules with distinct sizes were identified; the first (45-kb mtDNA) was found in all race A isolates and seven race 4 isolates, and the second (55-kb mtDNA) was found in all race 3 isolates and in two isolates of race 4. These two mtDNA molecules were closely related to mtDNAs of F. oxysporum isolates belonging to other formae speciales (conglutinans, lycopersici, matthioli, and raphani). Isolates within a VCG shared the same rDNA and mtDNA haplotypes, with the exception of VCG0114, in which three distinct mtDNA haplotypes were observed. Genetic relationships among isolates inferred from rDNA or mtDNA site restriction data were different, and there was not a strict correlation between race and RFLPs.(ABSTRACT TRUNCATED AT 250 WORDS)

DNA, Fungal↗
PubMed1988

Ontogeny of gonadotropic and thyrotropic cells in fetal mouse anterior pituitary. Comparison between two species C57 BL6 and Balb/C.

The fetal period constitutes a determinant stage in the ontogenesis of the hypothalamo-hypophysial-gonadal system. This work mainly concerns gonadotropic and thyrotropic functions and compares their different aspects in two strains of fetal mice. Balb/c and C57 BL6 fetal mice were studied at 16, 17, 18 and 19 days of gestation. The appearance and distribution of immunoreactive gonadotropic and thyrotropic cells of the anterior pituitary were observed by immunocytology using an indirect method with anti-porcine luteinizing hormone beta serum, anti-bovine thyrotrope hormone serum after saturation with bovine luteinizing hormone and anti-rat luteinizing hormone serum. In the two strains and in both sexes, LH gonadotropes appeared at 17 days of gestation and preferentially localized in the ventral part of the anterior lobe; a similar distribution was noted at 18 days and there was an increase in the number and staining intensity of labeled cells. By 19 days of gestation the gonadotrophs seemed more numerous, more generally distributed throughout the gland and often abutted to sinusoidal capillaries. An account of immunoreactive cells with anti-porcine luteinizing hormone serum and statistical evaluation of the results performed by variance analysis showed significant differences between the two strains. LH gonadotropic cells were always more numerous at each day of gestation in Balb/c fetuses especially in female fetuses. The possibility of a different evolution and/or differentiation for this cell population is discussed. Comparison of gonadotropic function between rat fetuses, mouse fetuses and human fetuses lead us to conclude that mouse fetuses appeared as an experimental model more closely related to human fetuses.

Animals↗
PubMed1988

LHRH-immunoreactive structures in the sheep brain.

Neural structures containing luteinizing hormone-releasing hormone (LHRH) are characterized in adult ewe and female lamb brains. Three anti-LHRH antisera are used in an immunofluorescent or immunoperoxidase method. On our preparations, all three gave the same results, expressed as number of labelled cells (about 2500 in a whole brain). It was found that 95% of the LHRH-immunoreactive cells are located in the preoptico-hypothalamic area, where cell bodies are localized mainly (50%) in the area surrounding the organum vasculosum of the lamina terminalis (OVLT); they are also found in a more anterior section of the medial part of the olfactory tubercle and the medial septum (14%), in a more posterior situation in the anterior and lateral hypothalamus (16%), and in the mediobasal hypothalamus (15%). Fibres originating in various part of the whole preoptico-hypothalamic group reach the OVLT and the median eminence. The remaining cells (5%) and fibres are found in various tel-, di-, and mesencephalic areas.

Animals↗
PubMed1987

Immunocytochemical demonstration of the presence of catecholamine and serotonin neurons in the sheep olfactory bulb.

The catecholamine and serotonin innervation of the sheep olfactory bulb was studied using immunocytochemistry. Specific antisera raised against tyrosine hydroxylase, dopamine beta-hydroxylase, phenylethanolamine N-methyl transferase and serotonin were used. Tyrosine hydroxylase-positive cell bodies were present in all cell layers except in the anterior olfactory nucleus, the greatest number being found in the glomerular layer. Neither dopamine beta-hydroxylase-positive nor serotonin-positive cell bodies were observed. Dopamine beta-hydroxylase-positive fibers were widely distributed in the granule cell layer but less widely in other layers. The glomerular layer contained the greatest distribution of serotonergic positive fibers, but such fibers were also visualized in other cell layers. No phenylethanolamine N-methyl transferase-positive structures were found in this investigation.

Animals↗
PubMed1987

Maturation of luteinizing hormone-releasing hormone (LHRH) and somatostatin (SRIF) neuronal systems in the hypothalamus of growing ewe lambs.

Using the immunoperoxidase method, neurons containing luteinizing hormone-releasing hormone (LHRH) and somatostatin (SRIF) were identified in the hypothalamus of growing ewe lambs between 3 days and 16 weeks of age. Both peptidergic neuronal systems were well developed in the early postnatal period. The centres producing LHRH were found to be situated in the anterior region of the hypothalamus and preoptic area. Immunoreactive (ir) LHRH perikarya in growing lambs were readily stained by the various anti-LHRH antibodies used and they were generally more numerous in young animals than in foetuses and adults. The concentration of irLHRH material stored in the median eminence (ME) increased with lamb age, reaching a maximum around 12 weeks of age. The centre producing somatostatin, situated in the anterior periventricular area of the hypothalamus, did not develop before the postpartum period. The irSRIF material in the ME was greatly depleted during the first neonatal days but regained its former level by 8 weeks of age. From 10 to 16 weeks of age, these stores in the ME were again depleted. The results show that the two neuronal systems investigated developed in a different way in the growing lamb. The secretory activity of these systems changed during subsequent periods of growth. The importance of these events in the processes of body growth and reproductive system maturation are still to be determined.

Aging↗
PubMed1986

Somatotrophs and lactotrophs in the anterior pituitary of fetal and neonatal rats. Electron-microscopic immunocytochemical identification.

The ultrastructure of immunoreactive somatotrophs and lactotrophs in pituitaries of fetal rats at 19, 20 and 21 days of gestation and on the day of birth was studied. Somatotrophs, first detectable at 19 days of gestation, undergo only minor modifications before reaching the structure described for adults. In particular there is an increase in the endoplasmic reticulum and Golgi apparatus. Lactotrophs, first identifiable in newborn rats, are very different in ultrastructure from adult cells, because the secretory granules are generally small, but variable in shape and size and the Golgi complex is prominent.

Animals↗
PubMed1986

Immunocytochemical localization of S-100 protein in stellate cells (folliculo-stellate cells) of the adenohypophysis in the monkeys Macaca irus and Cercopithecus aethiops.

With the use of an antibody against bovine S-100 protein, it was possible to reveal a characteristic cell type in the pars distalis and the pars tuberalis of the monkey Macaca irus. In the adenohypophysis of Cercopithecus aethiops, labeled cells were present in the pars distalis, pars tuberalis, and pars intermedia. These cells, so-called folliculo-stellate cells, were found in all pituitaries studied. Surprisingly, an antibody against human S-100 protein did not label the stellate cells of the adenohypophysis. However, in Macaca irus, this antibody gave a strong positive reaction with various other cell types (interstitial cells of the pineal gland, Müller cells of the retina, autonomic ganglionic cells, glial cells of the central nervous system, Schwann cells, Bergmann glia of the cerebellum, fat cells, reticular cells of lymphoid organs). By use of double immunoenzymatic labeling, it was evident that stellate cells are spatially related either to somatotropes, prolactin cells, "corticotropes", or to glycoprotein-containing cells. Thus, a specific relationship to a particular endocrine-cell type could not be observed.

Animals↗
PubMed1986

Calcitonin immunoreactive cells in prostate gland and cloacal derived tissues.

Calcitonin- and serotonin-storing cells have been immunocharacterized in prostate gland, urethra, urinary bladder and anal canal. In addition, a few hCG and somatostatin immunoreactive cells have been detected in prostate gland. All these cells were dispersed throughout the epithelial lining. In the anal canal, calcitonin cells were exclusively confined to the anal ducts and anal transitional zone epithelium. Calcitonin and serotonin cells were seen in some examples of prostatic adenocarcinoma. Combined techniques most often showed coexistence of calcitonin and serotonin immunoreactivities in the same endocrine cell. hCG immunoreactive cells corresponded to a subpopulation of serotonin-, calcitonin-storing cells. Calcitonin and serotonin cells were present in most organs which originated from the cloaca. In this territory, this distinctive endocrine pattern could be regarded as an excellent marker of cloacal derived tissues. These tissues constitute an additional site for extrathyroid C-cells. It is likely that calcitonin cells are a component of some prostatic adenocarcinomas.

Adenocarcinoma↗
PubMed1986

Immunohistological detection of methionine-enkephalin-like and endorphin-like material in the digestive tract and in the nervous system of the mussel: Mytilus edulis L.

Using the indirect immunofluorescence technique, methionine-enkephaline-like, alpha- and beta-endorphin-like peptides were detected on whole body sections of Mytilus edulis L. Met-enkephalin-like immunoreactivity was localized in the epithelium of the digestive tract, in the hepatopancreas, and in the nervous system. The immunoreactive cell bodies were very abundant in the anterior gastric epithelium, but sparse in the terminal portion of the digestive tract. By their basal processes the immunoreactive cells were in contact with a plexus of immunoreactive cells and fibers located in the connective tissue underlying the digestive epithelium. In the principal hepatopancreatic ducts, isolated cells showing met-enkephalin-like immunoreactivity were detected between the epithelial cells and the basal lamina. A few immunoreactive cells and fibers were observed between the hepatopancreatic tubules. The three pairs of nervous ganglia contained in their cortical layer numerous met-enkephalin-like immunoreactive perikarya. Their central area possessed fluorescent immunoreactive bundles of fibers extending to the commissures, the connectives, and the nerves. Met-enkephalin-like immunoreactive fibers were detected between the smooth muscle cells. At the surface of these smooth muscle cells, immunopositive met-enkephalin-like tapered nervous endings were observed. The alpha- and beta-endorphin antisera produced a positive immunoreaction in some gastric epithelial cells, in some perikarya of the pedal ganglia, and in some nervous fibers. The endorphin-like structures were far less abundant than the met-enkephalin-like structures, but very close to them.

Animals↗
PubMed1986

Immunocytochemical and ultrastructural evidence for supra- and subesophageal localization of the dorsal-body cells of the snail Helix aspersa.

Dorsal-body endocrine cells (DBEC) of the snail were studied by means of immunocytochemical and electron microscopic methods at different times of the reproductive cycle. They specifically bind the anti-methionine-enkephalin (vertebrate--opioid-pentapeptide) antibody and are located not only near the cerebral ganglia but also in the connective tissue surrounding the subesophageal ganglia. Ultrastructural characteristics of these subesophageal cells, however, confirm their clear identity with the previously described supraesophageal cells. The quantitative variations of their immunoreactive content allow us to postulate a likely involvement in reproductive physiology (mating and egg laying). These observations prove that the distribution of the classical "dorsal-body cells" is more extensive than has been admitted until now and that they synthesize methionine-enkephalin-like substance(s).

Animals↗
PubMed1986

Disturbance of a met-enkephalin-like hormone in the hepatopancreas of crabs contaminated by metals.

This study combines trace-metal analysis with an immunofluorescent detection of a methionine-enkephalin-like substance in the digestive gland of the shore crab, Carcinus maenas L. The crabs were taken from two sites: Saint Nazaire and Le Croisic, the first being polluted in comparison to the second. The experimental crabs were also taken in Le Croisic and contaminated with Cd, Pb, Cu, and Zn during 1 to 3 weeks in the laboratory. The immunohistological observations indicate a change in the localization of the immunofluorescent methionine-enkephalin-like substance in the cells of the tubules constituting the digestive gland. In crabs from the clean site, experimentally starved or not, the immunofluorescence appears mostly basal while it exhibits an apical localization in metal-contaminated crabs or crabs caught in the polluted area. The detected substance, the nature of which remains unknown, accompanies cytoplasmic secretory granules during their migration to the cellular apex preceding the apocrine secretion. This change of the immunoreactivity enables the detection of metal contamination but it is nonspecific and therefore, a general environment pollution could produce the same phenomenon. In the particular case of zinc, this alteration appears at a Zn concentration in seawater which does not disturb the natural level of this essential metal in the digestive gland of C. maenas.

Animals↗
PubMed1986

Endocrine cells in renal pelvis and ureter, an immunohistochemical analysis.

A systematic detection of endocrine cells in the renal pelvis and ureter was carried out, using Grimelius stain and immunohistochemical techniques. Ninety specimens of pelvic and ureteral mucosae were investigated. Throughout the pelvic urothelium, endocrine cells were very uncommon, patchily distributed, and serotonin-storing. They have been disclosed in only two cases among normal-appearing transitional epithelium. Whether cells so scanty are normal and permanent inhabitants of this territory is debatable. The material examined did not provide opportunity to demonstrate endocrine cells throughout the normal ureter. Surprisingly, one case of supernumerary ureter with an ectopic distal orifice into the urethra harbored abundant serotonin cells. This remarkable endocrine profile, which departed appreciably from that of normal ureter, showed a close similarity with that of the urethra. This raises the question whether such endocrine differentiation might reflect, for this ectopic ureteric bud, urogenital sinus origin rather than wolffian origin.

Fluorescent Antibody Technique↗
PubMed1986

Somatostatin and adrenocorticotrophic hormone like immunoreactivity in small cell carcinoma of the lung.

The immunocytological detection of adrenocorticotrophic hormone (ACTH) and somatotropin release inhibitor factor (SRIF) like immunoreactivity was carried out on tumour cells from bronchial brush smears in 39 cases of lung tumours. Results obtained were compared with the cytological and histological diagnosis and confirmed the high incidence of ACTH synthesis by malignant bronchial carcinoma cells: the same phenomenon also seems to occur for somatostatin. The concomitant detection of ACTH and SRIF like immunoreactivity seems to be highly suggestive of small cell carcinoma and indicates that the immunocytological detection of hormones carried out at the same time as cytological examination can improve the accuracy of the diagnosis.

Adrenocorticotropic Hormone↗
PubMed1986

Unusual endocervical polypoid tumor with endocrine cells: an immunohistochemical and ultrastructural analysis.

Light microscopic, immunohistochemical, and ultrastructural features of an unusual polypoid tumor of endocervix are reported. Numerous polypeptide hormone and amine-producing endocrine cells were disclosed. Main conventional characteristics were the architectural growth pattern, with infolding glands giving rise to small secondary glands, the hypermucinous benign-appearing epithelium of endocervical type, and, possibly, the stromal smooth muscle. Ultrastructural analysis showed a highly differentiated tumor. Glandular elements were surrounded by a basal lamina. Mucinous cells, several endocrine cell types, amphicrine cells, nonsecretory ciliated cells, ciliated mucinous cells, and possible reserve cells were observed. This tumor departs appreciably from normal mucosa and common varieties of endocervical polyp, particularly its distinctive endocrine profile. The present case does not correspond to a well-defined type of endocervical neoplasia. It shares morphologic analogies with mucinous tumor of ovary. The malignant potential of this lesion as well as its relationship with minimal deviation adenocarcinoma remain questionable.

Endocrine Glands↗