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P Motte

Publications and source records attributed to P Motte.

At least 19 recordsLinked to original sources
PubMed2002

Dopamine activates noradrenergic receptors in the preoptic area.

Dopamine (DA) facilitates male sexual behavior and modulates aromatase activity in the quail preoptic area (POA). Aromatase neurons in the POA receive dopaminergic inputs, but the anatomical substrate that mediates the behavioral and endocrine effects of DA is poorly understood. Intracellular recordings showed that 100 microm DA hyperpolarizes most neurons in the medial preoptic nucleus (80%) by a direct effect, but depolarizes a few others (10%). DA-induced hyperpolarizations were not blocked by D1 or D2 antagonists (SCH-23390 and sulpiride). Extracellular recordings confirmed that DA inhibits the firing of most cells (52%) but excites a few others (24%). These effects also were not affected by DA antagonists (SCH-23390 and sulpiride) but were blocked by alpha2-(yohimbine) and alpha1-(prazosin) noradrenergic receptor antagonists, respectively. Two dopamine-beta-hydroxylase (DBH) inhibitors (cysteine and fusaric acid) did not block the DA-induced effects, indicating that DA is not converted into norepinephrine (NE) to produce its effects. The pK(B) of yohimbine for the receptor involved in the DA- and NE-induced inhibitions was similar, indicating that the two monoamines interact with the same receptor. Together, these results demonstrate that the effects of DA in the POA are mediated mostly by the activation of alpha2 (inhibition) and alpha1 (excitation) adrenoreceptors. This may explain why DA affects the expression of male sexual behavior through its action in the POA, which contains high densities of alpha2-noradrenergic but limited amounts of DA receptors. This study thus clearly demonstrates the existence of a cross talk within CNS catecholaminergic systems between a neurotransmitter and heterologous receptors.

Action Potentials↗
PubMed1999

PLENA and FARINELLI: redundancy and regulatory interactions between two Antirrhinum MADS-box factors controlling flower development.

We report the discovery of an Antirrhinum MADS-box gene, FARINELLI (FAR), and the isolation of far mutants by a reverse genetic screen. Despite striking similarities between FAR and the class C MADS-box gene PLENA (PLE), the phenotypes of their respective mutants are dramatically different. Unlike ple mutants, which show homeotic conversion of reproductive organs to perianth organs and a loss of floral determinacy, far mutants have normal flowers which are partially male-sterile. Expression studies of PLE and FAR, in wild-type and mutant backgrounds, show complex interactions between the two genes. Double mutant analysis reveals an unexpected, redundant negative control over the B-function MADS-box genes. This feature of the two Antirrhinum C-function-like genes is markedly different from the control of the inner boundary of the B-function expression domain in Arabidopsis, and we propose and discuss a model to account for these differences. The difference in phenotypes of mutants in two highly related genes illustrates the importance of the position within the regulatory network in determining gene function.

Amino Acid Sequence↗
PubMed1998

STYLOSA and FISTULATA: regulatory components of the homeotic control of Antirrhinum floral organogenesis.

The identity and developmental pattern of the four organ types constituting the flower is governed by three developmental functions, A, B and C, which are defined by homeotic genes and established in two adjacent whorls. In this report we morphologically and genetically characterise mutants of two genes, STYLOSA (STY) and FISTULATA (FIS) which control floral homeotic meristem- and organ-identity genes and developmental events in all floral whorls. The morphology of the reproductive organs in the first and second whorls of sty fis double mutant flowers indicate that the two genes are part of the mechanism to prevent ectopic expression of the C-function in the perianth of wild-type flowers. This is verified by the detection of the expansion of the expression domain of the class C gene PLENA (PLE) towards the perianth. Interestingly, in the second whorl of sty and fis mutants, spatial differences in stamenoid features and in the pattern of ectopic expression of the PLE gene were observed. This suggests that, with respect to the negative control of PLE, petals are composed of two regions, a lateral and a central one. Mutation in ple is epistatic to most of the sty/fis-related homeotic defects. PLE, however, is not the primary target of STY/FIS control, because dramatic reduction of expression of FIMBRIATA, meristem identity genes (FLORICAULA and SQUAMOSA) and of class B organ identity genes (GLOBOSA) occur before changes in the PLE expression pattern. We propose that STY/FIS are hierarchically high-ranking genes that control cadastral component(s) of the A-function. SQUAMOSA as a potential target of this control is discussed. Retarded growth of second whorl organs, subdivision of third whorl primordia and the failure to initiate them in sty/fis mutants may be mediated by the FIMBRIATA gene.

Gene Expression Regulation, Developmental↗
PubMed1997

Divergence of function and regulation of class B floral organ identity genes.

Regulatory mechanisms controlling basic aspects of floral morphogenesis seem to be highly conserved among plant species. The class B organ identity genes, which are required to establish the identity of organs in the second (petals) and third (stamens) floral whorls, are a good example of such conservation. This work compares the function of two similar class B genes in the same genetic background. The DEFICIENS (DEF) gene from Antirrhinum, including its promoter, was transformed into Arabidopsis and compared in function and expression with the Arabidopsis class B genes APETALA3 (AP3) and PISTILLATA (PI). The DEF gene was expressed in the second, third, and fourth whorls, as was PI. Functionally, DEF could replace AP3 in making petals and stamens. The DEF gene's AP3-like function and PI-like expression caused transformation of fourth-whorl carpels to stamens. Like AP3, all aspects of DEF function in Arabidopsis required a functional PI protein. Surprisingly, DEF could not replace the AP3 protein in properly maintaining AP3 transcripts (autoregulation). Our data allow us to revise the current model for class B autoregulation and propose a hypothesis for the evolution of class B gene expression in dicotyledonous plants.

Arabidopsis↗
PubMed1995

Functional analysis of the Antirrhinum floral homeotic DEFICIENS gene in vivo and in vitro by using a temperature-sensitive mutant.

Flowers of the temperature-sensitive DEFICIENS (DEF) mutant, def-101, display sepaloid petals and carpelloid stamens when grown at 26 degrees C, the non-permissive temperature. In contrast, when cultivated under permissive conditions at 15 degrees C, the morphology of def-101 flowers resembles that of the wild type. Temperature shift experiments during early and late phases of flower development revealed that second and third whorl organ development is differentially sensitive to changes in DEF expression. In addition, early DEF expression seems to control the spatially correct initiation of fourth whorl organ development. Reduction of the def-101 gene dosage differentially affects organogenesis in adjacent whorls: at the lower temperature development of petals in the second whorl and initiation of carpels in the centre of the flower is not affected while third whorl organogenesis follows the mutant (carpelloid) pattern. The possible contribution of accessory factors to organ-specific DEF functions is discussed. In situ analyses of mRNA and protein expression patterns during def-101 flower development at 15 degrees C and at 26 degrees C support previously proposed combinatorial regulatory interactions between the MADS-box proteins DEF and GLOBOSA (GLO), and provide evidence that the autoregulatory control of DEF and GLO expression by the DEF/GLO heterodimer starts after initiation of all organ primordia. Immunolocalisation revealed that both proteins are located in the nucleus. Interestingly, higher growth temperature affects the stability of both the DEF-101 and GLO proteins in vivo. In vitro DNA binding studies suggest that the temperature sensitivity of the def-101 mutant is due to an altered heterodimerisation/DNA-binding capability of the DEF-101 protein, conditioned by the deletion of one amino acid within the K-box, a protein region thought to be involved in protein-protein interaction. In addition, we introduce a mutant allele of GLO, glo-confusa, where insertion of one amino acid impairs the hydrophobic carboxy-terminal region of the MADS-box, but which confers no strong phenotypic changes to the flower. The strong mutant phenotype of flowers of def-101/glo-conf double mutants when grown in the cold represents genetic evidence for heterodimerisation between DEF and GLO in vivo. The potential to dissect structural and functional domains of MADS-box transcription factors is discussed.

Base Sequence↗
PubMed1994

FIL2, an extracellular Leucine-Rich Repeat protein, is specifically expressed in Antirrhinum flowers.

The expression of the Antirrhinum gene FIL2 is affected in mutants of the homeotic transcription factor DEFICIENS. Northern and Western blot analyses showed that FIL2 in wild-type Antirrhinum flowers is expressed weakly in the petals and more abundantly in the reproductive organs; the gene is active in the filaments and anthers of stamens, and in the stigma and transmitting tissue of the carpels. The FIL2 protein is glycosylated with high mannose type glycan chains and is located in the middle lamella of the extracellular matrix. The amino acid sequence contains 10 tandem repeats, the composition of which is similar to the Leucine-Rich Repeat (LRR) motif found in mammals, Drosophila and yeast. The possibility that FIL2 might be a component of a cellular signalling mechanism, involving LRR-mediated protein-protein interactions is discussed.

Amino Acid Sequence↗
PubMed1992

GLOBOSA: a homeotic gene which interacts with DEFICIENS in the control of Antirrhinum floral organogenesis.

GLOBOSA (GLO) is a homeotic gene whose mutants show sepaloid petals and carpelloid stamens. The similarity of Glo mutants to those of the DEFICIENS (DEFA) gene suggests that the two genes have comparable functions in floral morphogenesis. The GLO cDNA has been cloned by virtue of its homology to the MADS-box, a conserved DNA-binding domain also contained in the DEFA gene. We have determined the structure of the wild type GLO gene as well as of several glo mutant alleles which contain transposable element insertions responsible for somatic and germinal instability of Glo mutants. Analyses of the temporal and spatial expression patterns of the DEFA and GLO genes during development of wild type flowers and in flowers of various stable and unstable defA and glo alleles indicate independent induction of DEFA and GLO transcription. In contrast, organ-specific up-regulation of the two genes in petals and stamens depends on expression of both DEFA and GLO. In vitro DNA-binding studies were used to demonstrate that the DEFA and GLO proteins specifically bind, as a heterodimer, to motifs in the promoters of both genes. A model is presented which proposes both combinatorial and cross-regulatory interactions between the DEFA and GLO genes during petal and stamen organogenesis in the second and third whorls of the flower. The function of the two genes controlling determinate growth of the floral meristem is also discussed.

Alleles↗
PubMed1990

The nucleolonema of plant and animal cells: a comparison.

Depending on the author and the animal or plant origin of the material under study, the term "nucleolonema" is used in different contexts and thus indicates nucleolar ultrastructures that are different. In this paper, we attempt to clarify this state of affairs and to propose a definition for the plant cell nucleolonema.

Animals↗
PubMed1989

Positive anticalcitonin immunoscintigraphy in patients with medullary thyroid carcinoma.

A cocktail of three monoclonal F(ab')2 fragments against three distinct epitopes of calcitonin or PDN 21 was labelled with either 111In or 131I. These F(ab')2 fragments, a control 125I-F(ab')2 fragment and 99mTc-pertechnetate were injected into four patients suffering from medullary thyroid carcinoma. Scintigraphy data were processed by energy factor analysis for an optimal separation of images corresponding to each isotope. The best tumor detection was obtained 1-3 days after injection of the 111In-F(ab')2 cocktail which clearly labeled the thyroid tumors in the four patients (smallest tumor detected, 0.6 cm) as well as lymph node and bone metastases. In the liver, positive detection was only successful with the 131I-labeled cocktail. These results were confirmed by counting rates of resected specimens which provided average specificity indices ranging from 3.3 to 13.1. Anticalcitonin antibodies could be particularly useful for immunoscintigraphy detection of residual or recurrent medullary thyroid carcinoma in patients with elevated calcitonin serum level.

Adolescent↗
PubMed1989

Value of venous catheterization and calcitonin studies in the treatment and management of clinically inapparent medullary thyroid carcinoma.

Seventeen patients with medullary thyroid carcinoma (MTC) underwent venous catheterization (VC) for sampling and serum calcitonin (CT) assay. The VC was performed either after an initial treatment in order to detect cervical recurrences and metastases (16 patients) or to prove abnormal CT thyroid secretion before any treatment (one patient). In 16 of the 32 tumoral localizations suspected by VC (50%), a tumoral focus was proven. For selective/peripheral CT gradient value superior to 2.50, 12 localizations of 12 (100%) were proven and for CT gradient value between 1.50 and 2.50, four localizations of 15 (26.6%) were proven. In six patients with exclusive cervical MTC secreting sites, treatment induced a total remission in two cases (12%) and improved in four cases (23%). The authors conclude that VC has a real value to localize MTC secreting sites. A total remission or an improvement can be obtained after treatment when VC detects exclusive cervical tumors.

Adolescent↗
PubMed1989

Radioimmunolocation of hepatic and pulmonary metastasis of human colon adenocarcinoma.

We have established a large library of monoclonal antibodies against a human hepatoma cell line called FOCUS. One such monoclonal antibody (SF-25) detects a 125-kilodalton cell surface antigen found on FOCUS cells. As both the liver and the colon are of endodermal origin, we examined the possibility of expression in colon adenocarcinomas. This antigen was found in all 23 colon adenocarcinoma tissues surgically obtained but was absent in the adjacent normal mucosal counterpart as determined by a direct radioimmunohistologic technique. In the present study, we have established a model for human metastatic colon adenocarcinoma using the LS 180 cell line. Athymic mice were further immunosuppressed by intravenous injection of anti-NK cell antibodies (antiasialo GM1). After 24 h, mice were injected with LS 180 cells either via the tail vein or into the spleen followed by splenectomy. Macroscopic pulmonary and lymphatic metastasis developed within 2-3 wk after injection of cells and 9 of 10 mice died with advanced metastatic disease 2-3 wk later. In addition, macroscopic hepatic metastases were evident in 4 of 5 mice 3-4 wk after intrasplenic injection. Both hepatic as well as pulmonary and lymphatic tumor spread was localized by nuclear imaging with 125I-SF-25. Furthermore, micrometastases were detected by autoradiography 5-10 days later. Monoclonal antibody SF-25 is a potential candidate for tumor localization and the experimental metastatic colon cancer animal model may be useful for treatment evaluation of monoclonal antibody SF-25 either alone or in combination with other monoclonal antibodies when conjugated to radionucleotides and chemotherapeutic agents.

Adenocarcinoma↗
PubMed1989

The development of a two-site enzyme immunometric assay (EIA) for calcitonin and its application in the measurement of the hormone in normal subjects, MTC-patients and post-menopausal women.

We have developed a sensitive, two-site enzyme immunometric assay (EIA) using high affinity monoclonal antibodies for the measurement of immunoreactive human calcitonin (i-hCT) and compared the performance of the assay with that of the conventional radioimmunoassay (RIA). The sensitivity of an overnight EIA (2 pmol/l) was comparable with the long incubation (7 days) RIA. Both, the EIA and the RIA have been applied for the measurement of i-hCT in three groups: normal volunteers (n = 53), post-menopausal women (n = 25) and patients with MTC (n = 20). The results showed that in all three groups, the level of i-hCT was somewhat lower than that measured by RIA due to its greater specificity. The EIA can provide an attractive alternative to the conventional RIA for both routine diagnostic work and physiological studies.

Antibodies, Monoclonal↗
PubMed1985

A target structure for a series of human cloned natural killer cell lines is recognized by both anti-TNKtar and 4F2 monoclonal antibodies.

It was shown recently that a surface antigen termed TNKtar was likely to serve as a target molecule for three distinct human NK clones expressing the same clonotypic determinant (termed NKTa) present on a 90 KD recognition structure. In the present studies, we investigated whether TNKtar and a previously described antigen termed 4F2 were related. Parallel immunoprecipitations from membrane lysates of the same cells showed that both anti-TNKtar and 4F2 Mab precipitate a heterodimeric structure which resolves as two bands of identical m.w. (40 and 80 KD) in SDS-PAGE analysis under reducing conditions. Sequential immunoprecipitations demonstrated that the two antibodies are directed at the same molecule. However, one antibody did not block subsequent binding of the other, and vice versa, suggesting that anti-TNKtar and 4F2 Mab are directed at two distinct epitopes of the molecule. Functionally, it was found that 4F2 Mab was able, as well as anti-TNKtar, to selectively block cytotoxic function of JT9 cloned cells. Furthermore, as reported previously for anti-TNKtar, 4F2 had no effect when additional NKTa-NK clones were used as effector cells in cytotoxicity assays. Finally, cold target inhibition assays were performed by using cold target cells precoated with either anti-TNKtar or 4F2 Mab. These experiments showed that preincubation of target cells with either antibody blocked their ability to compete with their radiolabeled counterpart. Such results further strengthen the hypothesis that the activation antigen recognized by both anti-TNKtar and 4F2 Mab serves as a specific target structure for NKTa+ NK active clones. We discuss the importance of previous data concerning the 4F2 molecule in light of this functional role, which had not been identified previously.

Antibodies, Monoclonal↗
PubMed1983

Catechol-O-methyltransferase activity and aminergic binding sites distribution in human peripheral blood lymphocyte subpopulations.

We have studied the binding of [3H]dihydroalprenolol, a beta-adrenergic ligand, and [3H]spiroperidol, a dopaminergic ligand, to human peripheral blood lymphocyte subpopulations. The catechol-O-methyltransferase activity on these different cells was also determined. On intact living cells, an unequal distribution of both beta-adrenergic and dopaminergic binding sites was found between B- and T-lymphocyte subpopulations. In each binding, T cells exhibited a lower number of binding sites than B cells. On particulate preparation, catechol-O-methyltransferase activity showed a similar distribution, but binding data with such material were quite different. Although it was not possible to detect dopaminergic binding sites on particulate preparation, T and B lymphocytes contained equivalent numbers of beta-adrenergic binding sites. Different explanations for these results are proposed.

B-Lymphocytes↗
PubMed1983

Production and in vitro utilization of monoclonal antibodies to human thyroglobulin.

Human thyroglobulin (Tg) was used as an antigen in the development of antibodies by the hybridoma technique. From four antibodies that bound more than 40% labeled Tg, two were characterized (182/E4 and 211/A5). They were both of the immunoglobulin G 2ab subclass, and provided an affinity constants (Ka) of 1.2 X 10(10) and 7.7 X 10(9) mol-1, respectively. The specificity of these antibodies was demonstrated by the absence of cross-reaction by monoiodothyronine, diiodothyronine, T3, T4, and sialic acid. A RIA was developed with 182/E4 or 211/A5, and the least detectable dose, based on the standard curve, was 10 ng/ml. The immunoreactivities of 182/E4 and 211/A5 to four Tg preparations different in iodine content appeared to be identical. Histochemical staining was used on normal and neoplastic tissues with both antibodies. Positive reactions were obtained in both cells and colloid, with heterogeneous staining from one follicle to another. Papillary carcinoma showed numerous positive cells, in contrast with Hürtle cell tumors which displayed very few positive cells. Anaplasic giant and spindle cells were negative. Monoclonal antibodies to human Tg are useful for in vitro detection of Tg.

Animals↗