J Y Toullec

Publications (11)35.89 Total impact

• Article: Molecular cloning and cellular expression of crustacean PC2-like prohormone convertase.

  J Y Toullec, N Kamech, D Gallois, M Maïbèche, V Papon, M Boscaméric, D Soyez
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  ABSTRACT: PC2 prohormone convertases are enzymes involved in the proteolytic maturation of neuropeptide precursors. In the present work, a cDNA encoding a PC2-like enzyme (OrlPC2) was cloned from crayfish eyestalk ganglia (medulla terminalis) containing the X-organ, a major neuroendocrine center. The predicted 634 amino acid preproprotein exhibits highest sequence identity, especially in the catalytic domain, with PC2s from arthropods and nematodes, and less with mollusc and vertebrate enzymes. It was demonstrated by in situ hybridization on crayfish medulla terminalis sections that OrlPC2 is expressed in a large number of neuron perikarya, including those producing the well known crustacean hyperglycemic hormone.
  Biochimica et Biophysica Acta 04/2002; 1574(2):145-51. · 4.66 Impact Factor
• Article: L to D amino acid isomerization in a peptide hormone is a late post-translational event occurring in specialized neurosecretory cells.

  D Soyez, J Y Toullec, C Ollivaux, G Géraud
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  ABSTRACT: Modification of the chirality of a single amino acid residue within a peptide chain appears to be novel additional mechanism leading to structural and functional diversification of eukaryotic bioactive peptides. This phenomenon has been studied at the cellular level in a neuroendocrine organ which elaborates a mixture of diastereoisomers of a 72-residue neuropeptide, crustacean hyperglycemic hormone. For the first time, amino acid isomerization has been shown to occur in the perikarya of fully specialized neurosecretory cells, as a late step of the maturation of the hyperglycemic hormone precursor and after propeptide cleavage. The specificity and efficiency of this phenomenon indicates the existence of a new enzyme family involved in the biogenesis of peptide hormones.
  Journal of Biological Chemistry 01/2001; 275(48):37870-5. · 4.77 Impact Factor
• Article: Crustacean primary cell culture: A technical approach.

  J Y Toullec
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  ABSTRACT: Crustacean cell culture has gained attention as a potent model to assist in the development of diagnostic reagents and probes for use in the shrimp, crayfish and lobster industries. The availability of such cellular tools is especially important to industries which use intensive aquaculture methods and thus have increased risk of disease problems. Indeed, crustacean cell cultures offer potential for studying the effects of pathogens in vitro and for increasing our knowledge on developmental and sexual maturation processes, or endocrine regulation in crustaceans. Although numerous attempts have been undertaken, no established cell line of marine crustaceans has been reported to date. However, primary cultures obtained from various organ sources are reported with increasing frequency. They represent the first steps towards the establishment of cell lines and they provide useful information concerning the most suitable cell culture conditions involved in the survival and proliferative capacity of the various tissues.
  Methods in Cell Science 02/1999; 21(4):193-8.
• Article: Combination of peptide profiling by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and immunodetection on single glands or cells.

  V Redeker, J Y Toullec, J Vinh, J Rossier, D Soyez
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  ABSTRACT: The combination of two sensitive and powerful analytical techniques on the same biological sample was examined: (i) matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), which gives informative peptide profiling on complex samples such as organs or cells; (ii) immunological tools such as enzyme-linked immunosorbent assay (ELISA) and immunocytochemistry to probe for specific peptides in biological extracts or cells. The cellular expression of the two precursors of the hyperglycemic hormone (cHH) was analyzed in neurosecretory cells (30-micron diameter) from the crayfish Orconectes limosus. Neurohemal organs were used to optimize the sample preparation and to demonstrate that, after peptide fingerprinting by MALDI-TOF MS, the sample can be recovered from the MALDI plate for further immunological analysis by ELISA. It was also established that, after immunocytochemistry following 4% paraformaldehyde fixation of the organ, the stained tissue could be recovered for further MALDI-TOF MS analysis. This dual characterization was successfully scaled down to the level of a single crayfish neurosecretory cell. Direct peptide profiling by MALDI-TOF MS on a single cHH-producing cell previously identified by immunocytochemistry demonstrated that both procHH isoforms were expressed in each cell analyzed.
  Analytical Chemistry 06/1998; 70(9):1805-11. · 5.86 Impact Factor
• Article: Involvement of a 3beta-hydroxysteroid dehydrogenase activity in ecdysteroid biosynthesis.

  C Dauphin-Villemant, D Böcking, C Blais, J Y Toullec, R Lafont
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  ABSTRACT: Ecdysteroid biosynthesis was analyzed in vitro using dissociated Y-organ cells from the shore crab Carcinus maenas. 3-Dehydroecdysone (3DE) was detected as a minor secretory product, in addition to the formerly identified end-products 25-deoxyecdysone and ecdysone (E). In conversion studies, 3DE was formed from tritiated 5beta-ketodiol (2,22,25-trideoxyecdysone), 2,22-deoxyecdysone and 2-deoxyecdysone but not from E. Further experiments were performed in order to understand the interconversions between 3-oxo and 3beta-OH compounds in the crab Y-organ. The enzyme involved in 3beta-dehydrogenation was not ecdysone oxidase, a soluble enzyme found in peripheral tissues of many arthropods but it presented strong similarities with 3beta-hydroxysteroid dehydrogenase enzymes from vertebrates: it was membrane-bound and NAD+-dependent. Moreover, a NADH-dependent 3beta-reduction of several 3-oxo-ecdysteroids was obtained using the same microsomal fraction (100,000 x g pellet) of Y-organs, indicating that the reaction might be reversible. As this activity was specific of molting glands, we hypothesize that there is at least one 3beta-hydroxysteroid dehydrogenase enzyme involved in the biosynthetic pathway of ecdysteroids.
  Molecular and Cellular Endocrinology 05/1997; 128(1-2):139-49. · 4.19 Impact Factor
• Article: Dissociated cell suspensions ofCarcinus maenas Y-organs as a tool to study ecdysteroid production and its regulation

  J. Y. Toullec, C. Dauphin-Villemant
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  ABSTRACT: In vitro ecdysteroid production by dissociated Y-organ cells of the shore crabCarcinus maenas was characterized during short-term incubations. Under optimized conditions (M199 adjusted to crab osmolality and with the addition of 10% foetal calf serum), ecdysteroid production by dispersed cells increased linearly during 4-hour incubations, with little intra-assay variation. 25-deoxyecdysone was mainly produced. PurifiedCarcinus molt inhbiting hormone (CamMIH) produced a dose-dependent inhibition of ecdysteroid production by dispersed cells. The cells were about 50 times more sensitive than whole glands to MIH. Other structurally-related peptides were tested.
  Cellular and Molecular Life Sciences CMLS 01/1994; 50(2):153-158. · 6.57 Impact Factor
• Article: The occurrence and in vitro effects of molecules potentially active in the control of growth in the marine mussel Mytilus edulis L.

  J Y Toullec, I Robbins, M Mathieu
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  ABSTRACT: A molecular with a molecular weight, estimated by gel filtration, of approximately 22 kDa and immunoreactive to anti-human hypophysial growth hormone (hGH) has been identified by radioimmunoassay in the digestive gland and hemolymph of the mussel Mytilus edulis L. The dilution curve of this molecule was parallel to that of hGH, suggesting that the antigenic site of the Mytilus molecule is similar to that of hGH. Immunoreactive fractions resulting from gel filtration failed to stimulate protein synthesis in dispersed mantle-edge cells in vitro. No hGH-immunoreactive material was detected in the cerebral ganglia. It is thus clear that a small protein-synthesis-stimulating factor (PSSF), identified in the cerebral ganglia and hemolymph by its action in vitro on dispersed mantle-edge cells, is not analogous to the Mytilus hGH-immunoreactive molecule. Likewise, a somatostatin-immunoreactive molecule present in the hemolymph of Mytilus did not coelute with PSSF. Evidence is presented that PSSF is a hydrophilic peptide that stimulates DNA, RNA, and protein synthesis and that is not tissue specific. These characteristics suggest that PSSF is a growth hormone.
  General and Comparative Endocrinology 07/1992; 86(3):424-32. · 3.27 Impact Factor
• Article: In vitro protein synthesis and alpha amylase activity in F cells from hepatopancreas of Palaemon serratus (Crustacea; Decapoda).

  J Y Toullec, M Chikhi, A van Wormhoudt
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  ABSTRACT: In crustaceans, all the steps in the assimilation of food take place in the hepatopancreas. To facilitate the study of this organ, a method for the dissociation of cell types was developed. The hepatopancreas of the prawn Palaemon serratus was mechanically dissociated and the cells separated by Percoll density-gradient centrifugation. The E and R cells had similar densities of around 1.05 g/ml. The F cells were separated into two distinct fractions with densities of 1.075 and 1.082 g/ml. The B cells sedimented at a density of 1.12 g/ml. The ratio between the two populations of F cells was found to vary during the intermolt cycle while B cells disappeared after the molt. When the density gradient fractions were incubated with 3H-leucine, incorporation was highest in the F cell fractions. Measurements of alpha-amylase activity, indicated that the two populations of F cells may be derived from the same cell type.
  Experientia 04/1992; 48(3):272-7.
• Article: In vitro protein synthesis and α amylase activity in F cells from hepatopancreas ofPalaemon serratus (Crustacea; Decapoda)

  J. Y. Toullec, M. Chikhi, A. van Wormhoudt
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  ABSTRACT: In crustaceans, all the steps in the assimilation of food take place in the hepatopancreas. To facilitate the study of this organ, a method for the dissociation of cell types was developed. The hepatopancreas of the prawnPalaemon serratus was mechanically dissociated and the cells separated by Percoll density-gradient centrifugation. The E and R cells had similar densities of around 1.05 g/ml. The F cells were separated into two distinct fractions with densities of 1.075 and 1.082 g/ml. The B cells sedimented at a density of 1.12 g/ml. The ratio between the two populations of F cells was found to vary during the intermolt cycle while B cells disappeared after the molt. When the density gradient fractions were incubated with3H-leucine, incorporation was highest in the F cell fractions. Measurements of -amylase activity, indicated that the two populations of F cells may be derived from the same cell type.
  Cellular and Molecular Life Sciences CMLS 02/1992; 48(3):272-277. · 6.57 Impact Factor
• Article: [Quantitative variations during the intermoult cycle of peptides related to human growth hormone in Palaemon serratus (Crustacea; Decapoda)].

  J Y Toullec, A Van Wormhoudt
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  ABSTRACT: Growth hormone-like peptides cross-reacting with an antiserum human specific were detected in the haemolymph, the midgut gland and stomach extracts of the prawn Palaemon serratus using radioimmunoassay. Parallelism was observed between the dilution sample curves and the hGH standard curve. Moreover, at least one peptide exhibiting a similar apparent molecular weight (22,000 daltons) with hGH was detected. In the three samples different amounts were detected during intermolt cycle: between 1.3 and 2.2 ng/ml in the haemolymph, 23 and 84 ng/g wet weight for the midgut gland, 12 and 71 ng/g ww for the stomach. The stages with highest values were respectively: D 1" and D 1"', D 1"' and D 2, D 3 and AB.
  Comptes Rendus de l Académie des Sciences - Series III - Sciences de la Vie 02/1987; 305(7):265-9.
• Article: Involvement of a 3β-hydroxysteroid dehydrogenase activity in ecdysteroid biosynthesis

  C Dauphin-Villemant, D Böcking, C Blais, J-Y Toullec, R Lafont
  [show abstract] [hide abstract]
  ABSTRACT: Ecdysteroid biosynthesis was analyzed in vitro using dissociated Y-organ cells from the shore crab Carcinus maenas. 3-Dehydroecdysone (3DE) was detected as a minor secretory product, in addition to the formerly identified end-products 25-deoxyecdysone and ecdysone (E). In conversion studies, 3DE was formed from tritiated 5β-ketodiol (2,22,25-trideoxyecdysone), 2,22deoxyecdysone and 2-deoxyecdysone but not from E. Further experiments were performed in order to understand the interconversions between 3-oxo and 3β-OH compounds in the crab Y-organ. The enzyme involved in 3β-dehydrogenation was not ecdysone oxidase, a soluble enzyme found in peripheral tissues of many arthropods but it presented strong similarities with 3β-hydroxysteroiddehydrogenase enzymes from vertebrates: it was membrane-bound and NAD+-dependent. Moreover, a NADH-dependent 3β-reduction of several 3-oxo-ecdysteroids was obtained using the same microsomal fraction (100 000×g pellet) of Y-organs, indicating that the reaction might be reversible. As this activity was specific of molting glands, we hypothesize that there is at least one 3β-hydroxysteroid dehydrogenase enzyme involved in the biosynthetic pathway of ecdysteroids.
  Molecular and Cellular Endocrinology.